Can someone help me with it!

Hello, I am using an HP Pavilion dv4 notebook PC. now here's the issue, when i turned on my laptop it powers up, but it wont boot lights are on even the caps-lock lights and numlk are blinking, it keeps blinking but it wont boot up i tried switching the RAM or removing the one and try each of them in every slot but still not booting up, how do i fix this, anyway sometimes it boot but after shutting it down and powering it up it wont boot again unless ill wait very long time, thank you you'r will be helpful to me.