My Iphone 3gs is completely dead?

Today I was using it with about 40% battery charge when suddenly it just turned completely off without saying powering down and became unresponsive to anything I did. (Ex holding down the home and power button 10 secs etc… ) When I got home to charge it nothing happened and the screen stays completely blank as if there's no power at all. I was wondering if this is a problem with a fuse board or if this is my battery. I would really like to avoid getting a new phone because I have a bunch of pictures and videos from the last 3 years that I don't want to lose. Any help or advice on what i could do would be greatly appreciated.

Added (1). That's great… But it doesn't answer my question. I can still by parts online so i just need to know if this sounds like a dead battery or another internal problem.

Yes, with the release of the iPhone 5, Apple has discontinued support with all models pre iPhone4. Upon battery drain they will cease to function.