Ok children, cool your jets... that is enough of that...
There are 3 things that could be the matter, and possible solutions to each of them:
1). The CMOS could have been surged and corrupted or erased. This can be cured by resetting the CMOS. You need to turn of the PC first. Then disconnect the power cord. Then locate the small (VERY SMALL) button on the motherboard near the BIOS flash chip or the system battery. With the power on the PC off, hit that button ONCE. Then restart and pray. If that button isnt there, do all the steps upto the button part, but instead, remove the system battery, then hold the power button down for 30-45secs, then put the system battery back in and turn it back on.
2). The surge damaged the Powersupply and blew the 5v/3.3v/12v rail(s), meaning a new PSU is needed. This could have also damaged the REST of the PC, meaning new parts are going to be needed for the nessecary repairs.
3). The surge could have initiated the sheet protection on the RAM, which will need to be released. To release it, unplug the PC, hold down the power button for 30-45 secs, and then take out your RAM. Put the RAM back in, then hold the power button for 10secs again. Then reset the CMOS, and restart and hope it works.