Likewise, my "0" button will not work. I push it but nothing happens.
Same for my "Space#" button,
Tried to open it up to see if the keys were just gummed up, but can not find a 3 prong screw driver that is required for the screw.
There are replacement batteries being sold by eBay sellers listed here in Cell Phones Etc. Click here to view them. You can go to your local hardware store. They should have the screw driver you need to open up your phone.