ISTR that when I moved Thunderbird between different versions of Windows, I had to manually correct paths, partially because XP put them under "Documents And Settings" and Vista, 7 et al use "Users". In principle, all the paths used in the profile should be relative (not absolute) and hence immune from this problem. But if you have ever manually re-located any profile folders, maybe it uses absolute pathnames. Additionally, I found that some add-ons aren't too clever and do use absolute pathnames to their own resources.

Also, check that the new installation hasn't placed the profile data one folder lower. As far as I can remember, XP put the profile folders at the same level as profiles.ini, whereas in my newer installations, there is a subfolder called Profiles which itself contains the profile folders.

So, XP:

...\profiles.ini
...\my_profile.default
...\my_other_profile

and in Vista, 7 etc:

...\profiles.ini
...\Profiles\my_profile.default
...\Profiles\my_other_profile

Thank you Zenos. What you say is quite correct, but I've already checked profiles.ini to make sure it's pointed to the right place. The fact that my address book is available would point to that being correct, wouldn't it ? In which case why no Folders ? I now see that my original profile.default had a folder called "Mail", which opens to sub-folders, which in turn contain my emails. The profile.default in the new TB has a "Mail" folder, but inside this is a (new ?) folder called "Smart Mailboxes" which is empty ! Should I try copying my old mail folder into "Smart Mailboxes", or should I delete "Smart Mailboxes" and paste into "Mail" as previous ? I'll investigate Smart Mailboxes & post back !

It seems that this thread is dealing with the same problem : https://support.mozilla.org/en-US/questions/1002714 but I can't follow the logic of the solution, I'll carry on looking !

Many of the threads on this Forum and others seem unhappy with Smart Folders, and I would prefer to keep my four email accounts separate (which is why I have four email accounts !) So it looks as though the Smart Folder needs to go. Can anyone point to a folder layout from the "Profiles" Folder down that works with Windows 7 and the latest version of Thunderbird ?

If the mail folder is empty, then your old profile information you copied was not complete. Did you perhaps copy it when Thunderbird was open?

Make a new copy that does contain the mail folder and it's contents.

Smart folders is simply a folder view. [View menu (alt_V) > folders> unified] you apparently prefer all.

Did you perchance update from Version 2 at the same time.

I've just about got there now, moving folders around (there appear to be three files per item) till they're more or less in the place where I want them in the Folder pane: (Tried to paste a screen print here, but no joy) Everything seemed to want to go into Local Folders, but I now have my four email accounts going into a single Inbox Folder, but in their own sub-folder. Strangely, the label for each is in a separate location. Still puzzled by the logic of the filepath within the profile file. Plenty of articles of where the Profile Folder should be, but nothing on the actual layout/construction of the Profile to get folders appearing where you want them ? Anyway, it's going to be next week before I can look anymore at this, so thank you for taking the time to respond. My research before all suggested that it was a simple matter of copying the profile to an external drive, reloading Windows and Thunderbird, and then copying profile back in. Its obviously far more complicated than that. I don't know what version I was on before, but the new one is 24.6.0