Computer will not shut down or reboot

the fan is running and there is power to the cd drive; I have a dell computer and the 3 4 is lit up on the front; just keeps flashing.

if yuo hav ethe manual, check and see what this means, most likely some component has gone bad, troubleshoot

I have come to the conclusion that I need to replace the motherboard after I found some other issue that happened. Thanks your all your help.

This kind of problem could be occured from a newly installed hardware, too (if your mobo doesn't like it). Just remove any newly installed things.

If you haven't installed nothing, check for viruses.

After all, a bios reset could help you, too (or not).. Anyway, try to figure out what really the problem is.

Best answer selected by tjledvina.