In the old days, they (the so called experts) used to tell us to reformat the hard drive and start over.
Now, when they don't know something, they tell you to reinstall the operating system.
If you...

I don't know why, but I had to use Iobit's free Unlocker program. It allows you to unlock and then move, delete, or copy any file or directory that's been locked by some other program.

Works like...