ok, in order for us to troubleshoot properly, can you give more info?
What Operating System are you using? When did this start? Did you install any software or hardware recently?
I dont want to sound like an ass, but this is the equivalent of calling a mechanic and saying "my car is making a sound, can you help me fix it"...We need as much information as possible, even if you think it's not important.
But going on the VERY limited information given, I would advise trying to start the computer in safe mode (if you're using windows). To start in safe mode, you need to hold F8 when you turn the machine on and you will be presented with the option to start windows in safe mode. If you have the option to do so, you should start windows in safe more (WITH NETWORKING)
so you can access the internet.
If you can start the machine in safe mode and are able to connect to a network, you need to download this program:
once you download it, restart the machine (not in safe mode)...let the blue screen happen. Then restart the machine AGAIN in safe mode, and open up blue screen viewer and highlight the most recent entry and screenshot it, like below:
I'll be able to get a better idea of what's wrong with the machine by looking at this.