Thanks Pete.
I was talking about whole OS. Computer was dying as I worked so I did an immediate backup before it turned into a brick.
I took the computer back to factory settings and I then restored data from back up. For some reason the db was not coming over.
I've resolved the issue. I restored all the Calibre libraries from my external drive and one of them let the data base restorer work.(I tried before but didn't get anything.)
I'm very happy
