computer wont boot up

I have very little computer knowldge, so there probably is a simple solution to my problem that I just havnt thought of but hopefully you guys can help.
Last night I shut down my computer as normal, today when I went to turn on my computer it seemed to start like normal, made all the right noises etc.. for about 4 seconds then the power light that should be green flashes red 5 times with 5 beeps for 5 seconds stops for 3 seconds then flashes and beeps again and again and again..... the fan is on and the monitor says no signal.