Well, hopefully they didn't have you delete all your settings!!

From inside Firefox, go to

Help > Troubleshooting Information > "Show Folder" button

this will launch your currently active Firefox personal settings folder, also known as your profile folder.

In there, you will see a folder named bookmarkbackups. If you look at the files in there, can you identify where the size dropped? You will want to restore the one just before the size drop. Make a note of the date coded into the file name.

This article has the steps for how to restore the desired backup: Restore bookmarks from backup or move them to another computer.

Any luck?

Regarding the delta-search problem, try disabling ALL nonessential and unrecognized extensions. Do not be fooled into thinking any of them are necessary if you did not choose them yourself and know what they do.

orange Firefox button (or Tools menu) > Add-ons > Extensions category

After that, depending on your symptoms, you might need to reset your home page, reset your new tab page, default your search services back to Google. Please briefly let us know what kinds of symptoms you have so we can point you to the right resources for the problem.

See also:

• http://kb.mozillazine.org/Lost_bookmarks
• https://support.mozilla.org/kb/Lost+Bookmarks

A few threads about Delta Search:

• [/questions/949921]
• [/questions/943111]