My mac crashed and it wont turn on again.

I was using my computer, and its been acting funny lately, some graphic problems but nothing serious, anyways safari closed up without any warning and then the unexpected quit message DID NOT show up, i couldnt open any other application, even though the dock worked just fine, so i kindly asked her to restart, and it didnt, then i tried to shut it down and nothing, it would just stay there. Then I just pushed the reset button on the button and then when it turned on I could see the grey apple and the little animation on the bottom but it just stays there, FOR HOURS I´ve restarted the RAM and the PMU and nothing works. Any tips??