If you test with another multimeter and they say no voltage, then the're dead. If however they read say 5v or higher, you may be able to revive them.
I had a pack which dipped too low for a normal lipo charge, but I read that a couple of minutes on a NIMH charge could get their voltage back enough for a regular charge. I did that, and after their voltage had picked up a bit, I then did a normal LIPO balance charge. That pack worked fine afterwards. Care must be taken with this process, as if they get left on NIMH charge for a full charge, it would likely not go well.
So if they are only a bit low, feel free to try this advice. You can probably find a more detailed guide somewhere on the web.
EDIT: I think I followed the MaxAmps guys advice on this thread.
http://www.rctech.net/forum/maxamps-...w-voltage.html