Shutting off. My battery will not charge at all and my computer gets hot and shuts off during use.

Question

My battery will not charge at all and my computer gets hot and shuts off during use. I can only use it for a few min before it shuts off on me. I am able to turn it back on, but I would like for the darn thing to stay on and I want to be able to use it without being plugged in! Can anyone help me fix the problem? Please...