So suddenly the power led of the case has turned off... no reason why apparently... because i didn't do anything, or case didn't suffer any hit... so what could have happened?
Pc turns on and works fine, it's just that light.
I would try and re-seat the front panel connector for that LED on the motherboard first. If that doesn't do it, either the connection to the LED is bad or the LED has stopped working. If the case is fairly new, you may can get an exchange under warranty if in fact the power LED is not working.
If you try to re-seat the power LED connection on the motherboard, gently bend the pins for that connection on the motherboard header outward slightly. Sometimes the pins on the motherboard don't make contact with the wires going to the particular front panel connector connections.