i have a samsung notebook computer and ance i turned it off it was just fine working correctly but when i restarted it it turned on but there was no display it had three lights but only 1 light was on.please help me

What model number is the computer?

Do you have an external monitor you can connect to it to see if that works?

Perhaps you have inadvertently pressed the keys that switched the display to an external monitor even though you do not have one connected? This is usually a Fn a Fn button plus one of the function (Fn) keys.

I think that you are right i once did press the (fn) button.but can you tell me how can I correct the problem.that the moniter will switch to interior again.thanks I am waiting for your reply

model of the notebook is samsung n150

The Users Manual is here (I think): Samsung Netbook N150-JP0A - N150-JP0A/JP0B - Netbook - notebook | SAMSUNG. It says Fn+F4 opens the Easy Display Manager window.

tried pressing fn+F4 key many times but nothing happens there is still no display.any other suggesions

Sounds like you need to take it to a reliable computer tech for servicing then.

Do you have another display you can hook to it or can you take it to a friends and try it. If that works then you know the computer is good but the LCD display is bad and needs to be replaced. A new one looks to be $50 to $60.