This might be caused by a firewall. In such cases, reinstalling often helps. You can download from http://getthunderbird.com/

Please postyour results

Thanks! The last time I had to reinstall I lost all of what I had archived. Basically had to start over. Will this happen again?

Here is the troubleshooting info. I copied to my clipboard:

 Application Basics

   Name: Thunderbird
   Version: 52.3.0
   User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0
   Profile Folder: Open Folder

             (Local drive)
   Application Build ID: 20170815040357
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory
   Profiles: about:profiles

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) pop3.mail.wowway.com:110, plain, passwordCleartext
     OUTGOING: , smtp.mail.wowway.com:587, plain, passwordCleartext, true

   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account3:
     INCOMING: account3, , (pop3) pop3.mail.wowway.com:110, plain, passwordCleartext
     OUTGOING: , smtp.mail.wowway.com:587, plain, passwordCleartext, true

   account4:
     INCOMING: account4, , (pop3) pop3.mail.wowway.com:110, plain, passwordCleartext
     OUTGOING: , smtp.mail.wowway.com:587, plain, passwordCleartext, true

   account5:
     INCOMING: account5, , (pop3) pop3.mail.wowway.com:110, plain, passwordCleartext
     OUTGOING: , smtp.mail.wowway.com:587, plain, passwordCleartext, true

   account7:
     INCOMING: account7, , (pop3) pop3.mail.wowway.com:110, plain, passwordCleartext
     OUTGOING: , smtp.mail.wowway.com:587, plain, passwordCleartext, true

 Crash Reports

 Extensions
   Lightning, 5.4.3, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Important Modified Preferences

   Name: Value

     accessibility.typeaheadfind.flashBar: 0
     browser.cache.disk.capacity: 358400
     browser.cache.disk.filesystem_reported: 1
     browser.cache.disk.smart_size_cached_value: 358400
     browser.cache.disk.smart_size.first_run: false
     browser.cache.disk.smart_size.use_old_max: false
     dom.apps.reset-permissions: true
     extensions.lastAppVersion: 52.3.0
     font.name.monospace.el: Consolas
     font.name.monospace.tr: Consolas
     font.name.monospace.x-baltic: Consolas
     font.name.monospace.x-central-euro: Consolas
     font.name.monospace.x-cyrillic: Consolas
     font.name.monospace.x-unicode: Consolas
     font.name.monospace.x-western: Consolas
     font.name.sans-serif.el: Calibri
     font.name.sans-serif.tr: Calibri
     font.name.sans-serif.x-baltic: Calibri
     font.name.sans-serif.x-central-euro: Calibri
     font.name.sans-serif.x-cyrillic: Calibri
     font.name.sans-serif.x-unicode: Calibri
     font.name.sans-serif.x-western: Calibri
     font.name.serif.el: Cambria
     font.name.serif.tr: Cambria
     font.name.serif.x-baltic: Cambria
     font.name.serif.x-central-euro: Cambria
     font.name.serif.x-cyrillic: Cambria
     font.name.serif.x-unicode: Cambria
     font.name.serif.x-western: Cambria
     font.size.fixed.el: 14
     font.size.fixed.tr: 14
     font.size.fixed.x-baltic: 14
     font.size.fixed.x-central-euro: 14
     font.size.fixed.x-cyrillic: 14
     font.size.fixed.x-unicode: 14
     font.size.fixed.x-western: 14
     font.size.variable.el: 17
     font.size.variable.tr: 17
     font.size.variable.x-baltic: 17
     font.size.variable.x-central-euro: 17
     font.size.variable.x-cyrillic: 17
     font.size.variable.x-unicode: 17
     font.size.variable.x-western: 17
     gfx.crash-guard.glcontext.appVersion: 45.2.0
     gfx.crash-guard.glcontext.deviceID: 0x0166
     gfx.crash-guard.glcontext.driverVersion: 10.18.10.4276
     gfx.crash-guard.glcontext.gfx.driver-init.direct3d11-angle: true
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle: true
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-d3d11: false
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-warp: false
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-try-d3d11: true
     gfx.crash-guard.status.glcontext: 2
     gfx.direct3d.last_used_feature_level_idx: 0
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 3458af34-84fa-4a27-99c7-0d9bb4c6700
     mailnews.database.global.views.conversation.columns: {"threadCol":{"visible":true,"ordinal":"1"},"flaggedCol":{"visible":true,"ordinal":"3"},"attachmentCol":{"visible":false…
     media.gmp.storage.version.observed: 1
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1503019636
     places.history.expiration.transient_current_max_pages: 132253
     plugin.importedState: true
     print.printer_HP_Photosmart_7510_series_(Network).print_bgcolor: false
     print.printer_HP_Photosmart_7510_series_(Network).print_bgimages: false
     print.printer_HP_Photosmart_7510_series_(Network).print_duplex: -2118647789
     print.printer_HP_Photosmart_7510_series_(Network).print_edge_bottom: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_edge_left: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_edge_right: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_edge_top: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_evenpages: true
     print.printer_HP_Photosmart_7510_series_(Network).print_footercenter:
     print.printer_HP_Photosmart_7510_series_(Network).print_footerleft: &PT
     print.printer_HP_Photosmart_7510_series_(Network).print_footerright: &D
     print.printer_HP_Photosmart_7510_series_(Network).print_headercenter:
     print.printer_HP_Photosmart_7510_series_(Network).print_headerleft: &T
     print.printer_HP_Photosmart_7510_series_(Network).print_headerright: &U
     print.printer_HP_Photosmart_7510_series_(Network).print_in_color: true
     print.printer_HP_Photosmart_7510_series_(Network).print_margin_bottom: 0.5
     print.printer_HP_Photosmart_7510_series_(Network).print_margin_left: 0.5
     print.printer_HP_Photosmart_7510_series_(Network).print_margin_right: 0.5
     print.printer_HP_Photosmart_7510_series_(Network).print_margin_top: 0.5
     print.printer_HP_Photosmart_7510_series_(Network).print_oddpages: true
     print.printer_HP_Photosmart_7510_series_(Network).print_orientation: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_page_delay: 50
     print.printer_HP_Photosmart_7510_series_(Network).print_paper_data: 1
     print.printer_HP_Photosmart_7510_series_(Network).print_paper_height: 11.00
     print.printer_HP_Photosmart_7510_series_(Network).print_paper_name:
     print.printer_HP_Photosmart_7510_series_(Network).print_paper_size_type: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_paper_size_unit: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_paper_width: 8.50
     print.printer_HP_Photosmart_7510_series_(Network).print_resolution: -2121268736
     print.printer_HP_Photosmart_7510_series_(Network).print_reversed: false
     print.printer_HP_Photosmart_7510_series_(Network).print_scaling: 1.00
     print.printer_HP_Photosmart_7510_series_(Network).print_shrink_to_fit: true
     print.printer_HP_Photosmart_7510_series_(Network).print_to_file: false
     print.printer_HP_Photosmart_7510_series_(Network).print_unwriteable_margin_bottom: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_unwriteable_margin_left: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_unwriteable_margin_right: 0
     print.printer_HP_Photosmart_7510_series_(Network).print_unwriteable_margin_top: 0
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_bgcolor: false
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_bgimages: false
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_duplex: -437918235
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_edge_bottom: 0
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_edge_left: 0
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_edge_right: 0
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_edge_top: 0
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_evenpages: true
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_footercenter:
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_footerleft: &PT
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_footerright: &D
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_headercenter:
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_headerleft: &T
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_headerright: &U
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_in_color: true
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_margin_bottom: 0.5
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_margin_left: 0.5
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_margin_right: 0.5
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_margin_top: 0.5
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_oddpages: true
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_orientation: 0
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_page_delay: 50
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_paper_data: 1
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_paper_height: -1.00
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_paper_name:
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_paper_size_type: 0
     print.printer_HP4E6A40_(HP_ENVY_5660_series).print_paper_size_unit: 0

I am puzzled why reinstalling Thunderbird would lose all your old data. If a profile exists in the correct location, Thunderbird should use it.

What exactly did you reinstall?

It was a few years back, so I cannot remember. Afraid to try again. I had folders of emails that I wanted to keep and they were gone.

OK, I re-installed and now it isn't even connecting to my ISP let alone downloading email. Before it would show "connecting to wowway.com" or something similar.

After I re-installed I had tried to download once and it didn't work, I tried again and lo and behold, it started downloading my email again after the re-install. Thanks, Wayne. And I did not lose anything this time. Everything is still there! I wonder if it was because my computer went thru. something called "Bad Pool Header", it stopped and went through some kind of fix and re-booted. The screen stated to go to www.windows.com/stopcode to find out about it. I did, but I didn't read all through it cause my problem was fixed. Anyhoo, thanks bunch for your help.