Are you trying to open a project with the xml extension in BAS? Probably your project is damaged, you did not edit it manually using text editors? Try to restore it from backups located here:
C:\Users\User\AppData\Roaming\BrowserAutomationStudio\projectbackups
@clarabellerising Already took these actions but didn't help. I've ended up reinstalling Windows. Now everything works. Hopefully won't have this problem again
