Computer wont start.. only fan keep running.. help~

Last night I put my computer into sleep mode and during the night, I accidentally unplug the power cord.. Next morning when I re-plug the power cord my window wont start.. When I push power only the fan is turn on..and it keep running.. but only black screen.
At first I though maybe my power supply unit is fried… I put in a new one but it is still the same…
Does it mean my mobo is fried??
Will someone help me out~
Thanks a lot!