i bet your BIOS is corrupted. this can happen if you have a drop in power or massive surge. these MSI boards are rather resistant sometimes and you have a good chance in recovering. try this:
unplug your power cord from your computer. then move the clear CMOS jumer to clear. leave it in the clear position over night or for a few hours. after that, move the jumper back to its normal positon and if it comes backup load your BIOS defaults and make sure BIOS PROTECTION is DISABLED. have a boot disk with the lastest BIOS on it and flash it. When using latest 2.3 version of the BIOS make sure that after you flash it move the CLEAR CMOS jumper to CLEAR; unplug the power cord from the power supply and wait about a minute.
If you have access to another MSI Nforce board then try to hot flash your corrupted BIOS. when the other MSI board is booted with a DOS disk remove the current new BIOS in the board and put in your corrupted BIOS and proceed to flash it like above. once you are done doing that put back into your current board without a BIOS. But, before you do this go ahead and try the new board's BIOS chip in your old one.
There is also a rescue procedure in flashing an AWARD BIOS when the system does not post anymore. it is on the MSI site:
www.msi.com.tw
if you cannot do that then take it back to the dealer you got it from and see if they can do a hot flash for you, swap out BIOS chips or a new board.