What should I do about my computer not turning on?

So a coouple days ago, my computer stopped turning on. I’ve checked the power supply while unplugged; you can still hear electricity in it when its turned on. By turned on, I mean the switch. It doesnt have the fan going or anything.

I’ve tried unplugging and replugging in all its connections.

I’ve tried changing the voltage setting on the power supply at each setting. None worked.

Useful info: the power supply is probably around two-ish years old, while case and the mother board are both 5 years old. And the power supply wasnt some cheap one, it was a pretty nice one.

More useful info: I don’t know if its my motherboard or my video card (probably my video card), but my screen has been cracking while playing games for atleast a year and a half. Also, icons on my desktop and basically any kind of graphic including banners on websites and such; even the home, refresh, and new tab buttons, etc.

Help please =( my life is terribly boring in the pm without a computer… And this one im on is god awefully slow… Like 10 minutes to boot up and 5 minutes to load a page, slow… T.t\

Thanks, and sorry for the essay. Any suggestions? Sadly, I’ve been jobless for almost a year, and I have no money to get it fixed, or to have someone look at it even. However, next month is my 18th bday…so im hoping to rack in some cash then.