Do you see a 'windows.old' folder on the desktop?

No, what do you mean Windows old folder? put it in Search and something is there

have this

'Windows.old' folder is usually in the 'C:' drive, same place as 'Program Files' folder, but sometimes it can be displayed on the desktop.

If you choose to “Keep nothing” when you upgrade Windows OS, or if you reset, refresh, or reinstall Windows, your personal files are temporarily saved to the 'Windows.old' folder for 28 days (unless you formatted your hard drive before installing in which case there is no old Windows to copy). If you decide you want some or all of these files back, you can usually retrieve them from this folder.

This link has info saying for Windows8.1 but it applies to Windows10 as well.

• https://support.microsoft.com/en-gb/help/17125/windows-8-restore-files-old-folder-upgrade

Good info:

• https://superuser.com/questions/1210451/what-does-windows-old-folder-contain

The point is this. If you can locate the 'Windows.old' folder it would contain all the old Appdata info including Thunderbird profile. Typically it would be here : C:\Users\<Windows user name>\AppData\Roaming\Thunderbird Then you can copy that Thunderbird folder and paste it back into your User Account> Appdata > Roaming folder overwritting the default one. Thunderbird program (if installed) would need be exited /not running whilst copy pasting.

Do not perform any clean up operation on computer as it may delete the 'Windows.old' folder.

Found a really useful link with some images...:

• https://answers.microsoft.com/en-us/windows/forum/windows_10-files/recover-personal-files-from-the-windowsold-folder/755e0ea3-b16f-4d5d-89b5-abecfbf68300