|"check the switch on the back, the volt switch 110~220,"|
If the system was working properly before the power outage how could the voltage selector switch possibly be in the wrong position?
I agree you may have had a powersupply failure. I disagree that the presence or absence of lit LEDs on the motherboard will be definitive evidence of it's status. Since the PSU provides voltage to the motherboard through several different output rails, it is distinctly possible for LEDs to be lit yet the PSU to have still failed on another rail.
There are a few methods available for testing a PSU but unless you have a load tester the simplest method is simply replacement. Once you have a known good PSU you can then determine if that was your only problem or if something else was damaged by the power fluctuation.
Goin' Fishin' (Some day)