i just got this new custom built PC.and the mouse and keyboard dont work. i should clarify the fact that to the extent of my knowledge they never did.my bro made the pc and has had it for a couple of months he got fed up with the mouse and keyboard so he was GOING to throw it away so i took it thats the only problem that i know of. so how would i fix this problem?If the mouse and/or keyboard are defective, you don't fix them; you replace them. If they're new enough you might still be able to get them exchanged.

Have you tried a different keyboard and mouse, just to make sure that the problem doesn't perhaps lie ELSEWHERE?i have tried different keboards and mice its in the compgraphics card missing.......or the on board one is not enabled.

more info needed.....on system used.....i am a bit of a noob so could u explain what u meen by
"on board one is not enabled"
also what do u meen by the system as in windows or who made it?Make sure they are plugged into the correct sockets.
(Look for little symbols near each socket)

Do they show up in your device manager?
(Start>Settings>Control Panel>System>Hardware)u know what my bro must of had them working at one time cause it has a password YES they are plugged in right i THINK he may have tuched the plugs (on the inside of the pc and done something)
is there a way to fix the plugs?
List make model of the motherboard ..........does it have a graphics card.....?maybe someone left it out of the build.it should have a graphics card.........and i dont know about the mother board (he made it in this summer program callede tech venture)Not so long ago we had a poster who had a keyboard/mouse problem, one of the very first responses was, "Are they plugged into the correct sockets?"
The answer was yes, 60 posts later... the answer was no.
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Do they show up in your device manager?
(Start>Settings>Control Panel>System>Hardware)

Do they show up in your device manager?  
(Start>Settings>Control Panel>System>Hardware)