I know how you feel when tech does this. I can only think you have clicked a combination of 2 or more keys together that is an actual command in Windows and Windows has responded to your unintended command. Otherwise i have no idea what has happened. I had all my stuff go missing a year ago after an update but restarting my computer not once, but a second time the next morning somehow made all my stuff come back. I don't know if the 'update' you have tried will interfere with this miracle working for you. Go into Firefox, go to those three bars in upper right corner, click Profiles then Manage Profiles. HOw many profiles are there? Assuming you have only ever used one profile, I'm wondering if a second profile has been created for some reason in the course of this keysmash of yours and your data is still intact in the old profile. so if there are additional profiles there, open them see if any are your old one. If you find it, make it the default (there should be an edit icon somewhere on that Profiles screen that will let you do that). If that doesn't work, there are other things that can be tried. Maybe others will be more techy than me and even know what happened.