Does the meter work when you put it on the other settings? (RF, SWR, etc.) If it does, then it's not the meter that's the problem and you're going to need to get someone to fix it for you.
However, if the meter doesn't work on any mode, then it's easy enough to fix. Before getting a new one open the radio up and find a little sticker on top of the meter. That sticker is covering up a little screw. The meter might just be stuck. You can try carefully loosening it up with a small screwdriver and see if that frees it up. Even a very small drop of oil might do the trick.