This one really stumped me, recently my father was working on his pc and then the screen went black like the computer was off yet the computer was on and making long beeps inside.The reset and starup buttons are unresponsive as well..I thought maybe it was the battery but when tested it had its normal 3v...Any help would be appreciated :D

specs:
p3 450mhz
512 sdram
win9x

Have you checked your monitor connection?..And was it making beeping sounds? I would make sure all your cable conections are properly fitted.

OOOps you did say it was making long beeping noises..Did you recently installed some hardware?

no from what I heard it just flat out went to black screen for no apparent reason..

This is a hardware problem and the beep code is the BIOS's message telling you what is the likely cause.
What is the exact beep code you hear? The exact code could point us to the faulty part.
See beep codes here:
http://www.computerhope.com/beep.htm
http://www.pchell.com/hardware/beepcodes.shtml

Download my diagnostic flowcharts from here www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip
and print them to leaf through.
Begin on the START UP chart.
1. Is the PC dead? I assume no. Do you hear the fans and are their lights?
2. Do you see any sign of the BIOS "polling" the hardware? [LED's blinking on various hardware like keyboard and drives] If so, it appears the BIOS ran the Power-On Self-Test [POST], found a hardware problem and sounded the beeps to warn you.
So the long or multiple beeps symptom take you to the NO POST chart.

NO POST
1. Their may be a Power Supply Unit [PSU] problem. It requires training and expertise to test an ATX PSU. [Which type does the PC have? AT or ATX?] You might be able to swap in a known good PSU, but best to leave this initially.
2. Disconnect all peripherals and adaptor cards except the keyboard and monitor, then restart to see if the POST succeeds or still gives the error beeps. If it does, then the board "or something on it" is faulty.
Since there would only be a few items still connected it narrows the field.
Retry startup after each of the following in any order convenient to you:
a. Reset to the BIOS default settings.
b. Keyboard: Swap for a known good keyboard.
c. Video card: You could swap in a known good card.
d. Memory: Beg or borrow some good replacement.

Now things get tougher.
e. You wouldn't happen to have access to a spare CPU perchance?

Inspect the motherboard to see if you can see anything obvoiusly amiss.
Particularly blown capacitors.
If none of that finds the fault then the board is probably faulty, cause as yet unknown.