[4x4.kid]

I've got an old Pentium 4 with 512mb of ram. I use it everyday and it didn't have any problems as it was running alright. We then went out of town for 8 days so before we left I turned off the computer and unplugged the AVR. When we got back, I plugged the AVR back and turned on the computer. I hear the computer turning on (the fans turn on, I hear the hard disk power up, the LED's of the CPU are on, the keyboard lights turn on, the monitor LED turns on, so does the light for the DVD Drive). However, nothing shows up on the monitor. The LED of the monitor turns orange instead of green meaning that it has gone into standby mode since it doesn't detect any input signal. I turn on the speakers and put it on full volume. I wait to see if I will hear the windows welcome tune whenever the computer starts. I wait for around 10mins and nothing happens. I try and press the eject button on the cd drive and on the DVD burner and nothing happens.(During normal use, I can open/close these drives even if I've just turned on the CPU and even if windows hasn't loaded.) I press the caps lock button/num lock button on the keyboard to see if their respective LED lights turn on and nothing happens.

So basically everything has power yet the computer doesn't boot and nothings shows up on the monitor. I hope someone enlighten me on as to what is wrong with the computer. Thanks in advance guys. I'm currently using my Dad's laptop to post on the net and search for answers.