- Close any Firefox windows that might be open.
- Click Windows Start at left end of Task Bar, put the following in Search Box or Run, and press [Enter]:
That should open an Explorer window with at least one Profile folder.
- Right-click on a Profile folder, and then click "Restore previous versions" in the pop-up menu to open the Properties window.
- Click to select the top (most recent) version, and then click "Restore...".
- That should pop up a confirmation window ("Are you sure you want to restore..."). Click Restore.
- Windows should then copy a bunch of files to restore Firefox, finishing with
"The folder has been successfully restored to the previous version."
- Click OK to close the message, then close the Properties and Explorer windows.
- Launch Firefox.
- "Restore previous versions" does not exist in Windows 8. Use File History instead.
- This procedure is covered in Windows 7 Help and Support under "Recover lost or deleted files" in the section "To restore a file or folder to a previous state".
- This only works if you have System Restore enabled and/or have used Windows Backup.
- You can try restoring an earlier version if necessary.
- If this doesn't work, you can start over by closing Firefox and deleting the Profile folder.