My computer won't work.

My computer has been really slow for a long time, and since my disk slot sometimes got stuck I didn't want to put in the disk that protects your computer.( I accidentally deleted the program) It's been running like that for years and nothing had really happened, a couple weeks ago I had a strange warning on my start up but gathered it was nothing because my computer worked fine. About a week ago my computer wouldn't turn on; but it turned out the start button was stuck and using a pen turned it on. I had just started up my computer a couple hours ago to get another warning, I didn't understand it so I ignored it although it said something about my computer's battery being low or low in space or something. However my battery was fully charged. If my laptop over heats or runs out of battery it takes a few seconds to shut itself down, that's normal. I was playing my games then all a sudden in a blink of an eye my laptop was off so I knew it had nothing to do with over heating or low battery power. I've been trying to turn it on all different ways for an hour now, it won't start up at all. My mouse that I have plugged in still has a red light too, please what do I do? My family doesn't have a lot of money so we can't just go try and get it repaired or get a new laptop. All I know is that my laptop is HP but I don't know about anything else. Please help me get it started again.