laptop screen stays black

[Sanjay07]

I have purchased new dell laptop
with Win 8 64 bit, 4 gb DDR3 , 1 Tb HDD , 2gb graphics card
When I closed laptop lid and reopen it after about 7 to 8 hour it stays black. Is it any hardware problem or settings problem? What should I do? Please help!

 

[jarotech]

When you open the lid push the power button.

 

[Sanjay07]

When you open the lid push the power button.

It didn't help me. I've already checked power settings of the lid, I didn't click any options for sleep the laptop when it's plugged in.