i take it its a beep before it starts up?? if so then im not getting that.
ok. Basically, the PC does a Power On Self Test (POST) when it starts up. The speaker on the mother board (if installed) will give one short beep if everything is ok. If theres a problem that it can detect it will give a series of beeps to indicate whats not working correctly.
If you're not getting any beeps at start up it could be that the machine isn't actually starting. Hence whys theres no picture on the monitor.
If I where you, I'd have a look inside the PC case and see if you can see the speaker. If you can follow the cable from it and make sure thats its plugged into the mobo.
If the speaker is installed and plugged in and you still don't get a beep, you have a harder problem to solve. The best thing to do would be to remove everything from the motherboard (expect the CPU) and power it on.
You should get a series of beeps then telling you that you have no RAM, Graphics card and HDD's. The you can start putting stuff back in powering it up each time to check that its working. You then finally find out what card/hardware is causing issues.
If you have no speaker on the mobo do you have any LEDs on the board it's self??
Some boards have four led lights that show in different configurations depending on whats not working on your machine.
hope it helps.