my computer doesn't boot right, i can't see anything cuz i have a black screen when booting. the cpu makes beeps but after around a minute it shuts down alone. what can i do? please help!

Please provide us with more information:

What is the model of your system?
Have you recently added any hardware?
Has anything recently changed, with regards to the computer's setup?

i actually fixed it it was the power supply it seems that the old one didn't generate enough energy. thanks anyway

Great! Thanks for posting back!