Thermal Grease

just want to know what will happen if the thermal grease on the processor wiped out??

b'coz i cleaned the heat sink, eventually I on the computer then it doesn't boot up.

thnx ...

"just want to know what will happen if the thermal grease on the processor wiped out??"...
The CPU probably overheated. If you didn't apply new thermal grease, The CPU may be permanently damaged

You will see increased temps on your computer.

However, modern CPUs (unless you're running a 486 you should be running one) should have overheating failsafes. Permanent damage doesn't seem likely to me. You're more likely to get random rebooting of your comp when you're running CPU intensive programs.

My bet is you probably dislodged something cleaning out the heatsink, but I can't reach that conclusion without knowing exactly what you mean by "eventually I on the computer then it doesn't boot up."

Yeah you might have damaged the motherboard and/or cpu by toying with it more than temps alone. Thermal grease is there for a reason...to transfer heat off your CPU.
When does it fail to boot up? If it just doesn't turn on then its unlikely to be a heat issue.

the computer won't on/operate/boot/run?? when I press the power button of the UNIT, the LED ( LED that symbolizes the computer is reading ) will just blink once. then nothing will happen . no display.

it fail to boot up since i on it.

on the bright side, your psu is still working. but it seems you may have damaged something.