If Firefox starts up after an update without your bookmarks and other settings, check whether your data is available in a different profile:

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it. The About Profiles page will open. This page should list at least one profile and could list many.

The profile that Firefox is currently using will show:
This is the profile in use and it cannot be deleted.

Please do not delete anything here; don't use any Remove buttons.

Do you have another profile named default or default-longnumber listed on this page? If so, you can check whether it is the one you were using recently by clicking its Launch profile in new browser button.

If it isn't what you want, simply close that new window.

If it IS what you want, click the Set as default profile button for that profile on the about:profiles page. Firefox will use it automatically at the next startup.

For more information see Recover user data missing after Firefox update.

Note: If your bookmarks are not available in another Firefox profile, see Recover lost or missing Bookmarks for other solutions.

The only profile available is my default one. History and bookmarks are gone and I cant add new ones. I'm logged out of all my accounts too. Not a single backup file on my computer to restore too. In december I switched computers and I logged in to the old one for the first time this week. Not sure if the log in will have affected the Mozilla data on the new computer? I tried to transfer a json file to this new computer with all the bookmarks but I am not allowed to manouver within the restore file section.

Hi,

Don’t panic — this usually happens after an update but the bookmarks aren’t always permanently gone. First, try pressing Ctrl + Shift + B to open the Library and check if they’re still there but just not showing on the toolbar.

You can also go to Bookmarks > Manage Bookmarks > Import and Backup > Restore and see if there’s an automatic backup available from a previous date. Firefox normally creates backups on its own, so there’s a good chance you can restore them from there.

If that doesn’t work, check whether Firefox created a new profile during the update — sometimes it switches profiles and your old bookmarks are still in the previous one.

Hope you’re able to recover them!

I have no other profiles after I checked. And I can't go in and choose a file to restore. There are no files and I cant even move around to find the json file I created and moved from my old computer.