Hi Mark, what method did you use to reinstall it? The Windows "Refresh" or "Reset" should preserve your data in a folder named

C:\Windows.old

Can you find such a folder on your system?

If so:

Before proceeding, please set Windows to show you hidden files and folders: https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

Then check here:

C:\Windows.old\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles\

You might just have one profile folder, or you might have more than one. The bookmark backup files are in a folder named bookmarkbackups in each profile. The creation data and number of items is coded into the file name. You can copy promising files to the Desktop to try in a Restore.

Anything so far?

Thanks - I didn't reinstall it. I was having problems with the PC so it was taken away for repair. I think most things were wiped from the PC. The folder Windows.old is not there.

Contact the repair center and ask questions. If they wiped the drive . . . .