It really depends on how your file became corrupted or damaged. Some files can be fixed by opening them in the desktop Adobe Reader product and saving the file. The desktop can repair some corrupted files. If you have a file that the mobile Reader is not opening correctly, it would help us if you could share it by email to firstname.lastname@example.org, along with a reference to this forum conversation.
I have a corrupt file that I would love to send to you to examine. Problem, you need to be able to open the file in order to have the email option...unless there is another way that I don't know about.