Apparently you have lost the diagrams for your subVIs. This is not a good thing at all. Try to find the original code (you DO have some kind of archiving or backup in place don't you) and restore those.
If this doesn't work, you may just have to start over, and consider this a lesson learned. Sorry to be the bearer of such bad news.
If nothing else, post the code here (along with what version they are written in) and maybe someone here can help you.