Computer screen is black

So I came back from a 10 day trip out of the country and I turn on my computer and the screen just stays black. When I turn it off by pressing the off button on it a blue / black screen comes out and at the bottom is says "windows vista home premium" for a few seconds and then shuts off.

I'm wondering if anyone knows what to do? I tried unplugging it and restarted it a few times.

Any help is great, thanks :)

my parents tampered with my computer when they cleaned my room, but i fixed the problem, it was with monitor.

congradulations on fixing it. happy computing