Computer powers on, but does not boot

Hello,

I've had this computer for maybe about a year now, it worked fine but now it work work anymore. One day I put my computer into sleep mode and went to eat dinner. When I came back, pressed my mouse, the fan started running louder than normal. I decided to close my computer and restart it. When i restarted it, there was a long beep, not a permanent beeping noise though.I didn't see the lights turn on, the i can hear the fan and everything but the lights didn't turn on. When i started my monitor it didn't show anything and said "No Signal". I didn't know what to do anymore. I thought maybe after 24 hours it would hear itself up, but it didn't. Please help me!