PC Desktop

I have a desktop with windows xp service pack 2 I am not sure what is wrong I had a blue screen that said Hardware Malfunction and I powered it off and restored my system to a later date as far back as I could since then it powered up once again and was fine for a couple hours I shut it down and it no longer will start up when I push the power button I can hear the fan start and it sounds like it is going to start up but it does not communicate with the keyboard or the monitor? Is my system still saveable? It is a home made computer it has a server motherboard installed with 4 GB ram (i think?) It was a really fast computer until all this happened Any advice will help
Thanks
Mayela