The Phone won't charge

I got this phone as a backup phone and I have had it for almost a year and never used it. I put the battery in it and it would not turn on, so I charged overnight with the charger that came with it and it still will not charge. I have even switch wall sockets to see if that was the problem. It will come on and shut right back down because of low battery. What could be the issue I would think I would need a new battery being that I have never use the one that came with the phone?