i was playing a game on my pc when it turned off and when i re started it the screen came back on the colour was bad and the brightness was way too high
I'm no expert but it sounds to me your graphics card may need upgrading. Perhaps the graphics on the game you were playing was too demanding for the graphics card on your pc. As I said I'm no expert so its just a suggestion.
Find latest drivers for your graphics card. Install them, reboot, try again.
If you don't know what graphics card/chip you have -> go to run, type dxdiag, hit enter, click display tab, look what it says next to Name: