Sorry to hear about this problem. Did Firefox mention at startup that it needed to create a new profile or perform a tune-up, or did it simply start up normally -- without your data?

If you haven't already, I always suggest as a starting point closing out of Firefox and doing a normal Windows shutdown and restart to complete any pending updates, release any file locks, and hopefully bypass any privilege/permission issues that could prevent Firefox from accessing its data.

If Firefox again starts up without your data, could you check whether your stuff is available in a different profile, as follows:

Profile Manager Page

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

This page should list at least one profile and could list many. (Each profile has two folders and one or more buttons. Do not use any Remove buttons!)

The profile that Firefox is currently using will have this:

This is the profile in use and it cannot be deleted.

Do you have any other profiles 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, back on the about:profiles page, click the Set as default profile button for that profile so Firefox uses it automatically at the next startup.

Any progress so far?

Hello Thanks for your answer. Restarted windows but no pending updates. And Firefox started "normaly" but not with my profile and not my other profile. Had two. Using "about:profiles" gives me two profiles. Default that cant be removed and another one that also seems to be new. None of my old profiles. Checking folders I found one of my old once and might also have found my old default one with another name. Copied those to the folders shown when checking "about:profiles" and restarted Firefox. But they are not there cant change to them. So how making them visable in "about:profiles"? Maybe using a checkpoint in windows and go back to old can be an option?

Checking folders I found one of my old once and might also have found my old default one with another name. Copied those to the folders shown when checking "about:profiles" and restarted Firefox. But they are not there cant change to them. So how making them visable in "about:profiles"? Maybe using a checkpoint in windows and go back to old can be an option?

Here's how you can add a folder to the list that Firefox is aware of: https://support.mozilla.org/en-US/questions/1307435#answer-1356183

I don't recommend System Restore because you often lose other data that way. However, there are tools to explore restore points and extract files from them so you can selectively restore data. See: https://support.mozilla.org/en-US/questions/1344344#answer-1428658