will not boot up
When trying to open firefox the following message appears.
Firefox is already running, but not responding. The old Firefox process must be closed to open a new window. If I pic Close Firefox the error message goes away but comes back. I've tried uninstalling and reinstalling with and without resetting to default but no help. Same issue appears.
Try to delete parent.lock in the profile folder.
Location used for the main profile that keeps your personal data.
You can create a new profile as a quick test to see if your current profile is causing the problem.
See "Creating a profile":
If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.