Did the Window repair tool give you choices about preserving your data? Many times Windows will create a 28-day temporary folder named

C:\Windows.old

with a copy of most of your application data in there.

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\

If you find recent data there, please pause and we can suggest how to resurrect your saved files.

Did the Window repair tool give you choices about preserving your data? Many times Windows will create a 28-day temporary folder named C:\Windows.old with a copy of most of your application data in there. 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\ If you find recent data there, please pause and we can suggest how to resurrect your saved files.

Yes it did preserves my data and I found the hidden files you told me about. What should I do now ?

You can manually copy/paste valuable data files from the old profile to the new one, as described in this article:

Recovering important data from an old profile

Alternately, you can try a complete "folder transplant" as outlined in the solution in the following thread:

https://support.mozilla.org/questions/1321847