Gigabyte GA - H77 - D3H does not boot

[eng.ahmednasr]

Dears,
after many power outage my PC could not boot, it gives the first beep then the startup screen which not responding to the "dell" or "f9,12" "end" but alt+Ctrl+dell is working
then the second beep and after about 20 sec the last beep and the screen go black

can anyone help

 

[rocktalkrock]

Have you cleared the CMOS?