the more times he will run, and work on the system, a chance to recover of the files will be smaller
Thanks for the tip, I didn't know that. As for restoring the system, I looked into the System Restore in the Control Panel, but there weren't any restore points. I also right clicked disk C and tried to restore to a previous version, but there weren't any too. I must have stupidly messed with some settings long ago and forgot about it.
Thank you both for your help and your time, but it seems the problem is bigger than I thought. The laptop keeps crashing and is making strange noises, so I can't do anything with it. Hope it can be repaired, and if the bookmarks are lost, it'll just be a painful lesson for me. Never forget to make backups 😉