HELP!

I have backed up all my sheet music/books (nearly 12,000 titles in all) and saved to a CD. Tonight I wished to alter some of them but was informed they are "Read Only" files and cannot be edited. Despite removing the tick in the "Read Only" box, I am still locked out. Is this normal, or is there a way of overcoming the "Read Only" Mode?

I would very much appreciate a reply if anyone has the answer.

Thanks!

Aud