laptop does not boot

I have hp probook 4520s lap. But now it does not boot. When I press switch on button fans are working but it shows black screen. HDD light just blink one or two times when start but it will not continue. And usually web cam light should blink one time when startup but it doesn't. I connect to different monitor but couldn't see a output.

This lap bought 3 months before but it doesn't have international warranty. Therefore I can not do anything. If someone can provide any clue or suggestion that what happened and what should I do, appreciated.

thank you.

If the machine got dropped or a bit of a knock, it might have unseated the memory. You could try opening up the memory socket and take out the memory and reseat it.

Sometimes removing the battery and starting it with the powersupply connected helps.