What color are the diagnostic LEDS on the front of the tower? If not all green, look up error codes here:

http://support.dell.com/support/edocs/systems/dim5100/en/sm/tshoot1.htm#wp1120147

Ron

If i were able to see the lghts I would be able to check but nothing at all happens when i press the on button. No lights sounds nothing

Have you plugged the PC directly into the wall, without power strips and surge protectors? Not trying to be mean, but I have to ask: Is the PC power cord still plugged into the back of the tower? ;)

If you peek into the case, do you see a green LED on the motherboard?

Ron

Yes I have tried to plug it directly to the wall and nothing, and yes it is plugged in the back because I do see a green light on the motherboard so I am puzzled on to what to do Ruben

Ok, was just checking for the simple solutions. If you're still under warranty, contact Dell Tech Support.

You can try testing the power supply by unplugging the 20 pin connector from the motherboard and jumping the Green wire to one of the Black wires, if the power supply and/or case/processor fans run, then you know it's good. Note: Do not remove any wires from the plug, use a small piece of wire or a paper clip as a jumper. And be careful working around electricity.

If power supply works, look around and make sure all the other connectors are in place. Check the ribbon cable from motherboard to the front panel. Carefully remove and reseat the connectors at both ends. If nothing helps, then you may have to consider it's a failed motherboard. :(

Contact Dell Spare Parts for a replacement motherboard, and compare prices with this:
http://www.softarcade.net/Motherboards_c_3817-1.html

Ron