martin - 2014-03-16

Dear all,
I need urgent help to solve the following problem: several weeks ago I did a back-up copy of all my work files compressing them with 7-zip. When I tried to re-open them I got the message that the files are damaged and they can't be opened. Do you know how to solve the problem? Do you know any program to repair the compressions made with 7-zip? It is urgent!
Many thanks in advance!!

pd: by the way, my operating system is windows 7