Computer acting weird for unknown reason

Earlier today, (around 4:30 pm), I was using my computer like always; it was working fine, there was nothing out of the ordinary. I accidentally let it run out of charge, so I plugged it up and left it while I went about my daily routine. Occupied by other things, I did not use the computer or turn it on again until, like, 10 minutes ago.

When I first turned it on, the keyboard was not working. Like, at all. Nothing would happen when I pressed any of the keys. I brought this problem to somebody else in the house with me, we turned the computer off (the power key wasn't working either, but we found a clickable icon to do it), and turned it on again.

When it came back on, the keyboard was working - but the computer itself kept randomly going off, only seconds after we got it on. This happened a few times; then we tried plugging it in, and we managed to keep it on for a short while - but once we unplugged it, it went off again. It's been on for a fairly long time now, plugged in - but I'm afraid to try unplugging it!

It's really confusing and frustrating - I swear I didn't do anything to damage it before this happened, and it wasn't acting weird at all the last time I used it. The only thing I did out of the ordinary was let it run out of charge, and then I didn't touch it until now, when this happened. Does anybody know what might be going on?