Before performing any of the following steps, make a BACKUP copy..
Once you have your backup perform the following steps.. At any stage if they seem to work then you can stop the steps..
Step 0 : After copying it to a new location. Try Publishing.
Step 1 : (If still error) Simple try compiling the Code, if there are errors correct them. Try Publishing.
Step 2 : (If still error) Try a Compact and Repair.. Try Publishing.
Step 3 : (If still error) High possibility the code is corrupted.. Try a Decompile.. Read the link on How to perform a decompile. Try publishing now. This should have sorted it.