Hey, just wondering if anyone know solution of my problem.
I use Dell Inspiron laptop. It has 2 video cards. integrated Intel HD and GeForce GT525M (they switch when any game is turned on). In order to check something out I turned off the Inel one and the screen went black. I managed to run WaW blind, I can hear the main menu but nothing appears on the screen. Thought it would force the laptop to use GeForce card, seems like it did but as I said I still see nothing.
Seems like all I need to do is to turn Intel card on again but i don't know how. I also tried to enable it with bios but found no option to do so.
Any ideas?

Im not sure if Dell does the same thing, but the systems I work with, if you have integrated graphics on your system, the only way I know to turn it off is through the bios.  I would suggest going into your bios setting and see if there is a way to disable the iGFX that way.  But I would do some google searching or contact dell directly to verify.

It would be under onboard devices if listed.

Well, it was listed in my device manager and that's how I turned it off. I was looking for the solution but found nothing sure.
There is nothing about enabling/disabling GPU in my bios...

Well I dont think it would show up as a GPU, since the iGFX is based off the CPU.  LIke Bones said, its probably going to be listed under onboard devices and probably be labeled "Internal Graphics"  What laptop model do you have.  Maybe I can find something.  No promises, but my google-fu is strong.

It's Dell Inspiron N5110

So I did a quick review.  

Looks like a few ppl have had the same question as you.  

A few things to try:
1. Make sure you have the most up to date System Bios from dell.com
2. Make sure you have the most up to date Intel & nvidia graphics drivers from dell.com.

Once you've dont that, this is something that I found for you:

Right clicked on a Desktop Icon and you should see " Run with Graphics processor " option.

Click on it and you should see there are 3 optoins, find the one that reads " Change Default Graphics processor"

Change the default to NVIDIA

I think my drivers all up to date.

The problem is I can't see.

"The problem is I can't see"

As if you visual issues with your eyes or the OS is not displaying anything on your display?

When I turned Inel off I hoped to force OS to use nvidia but instead of that the screen went black and nothing is displayed

Sorry I had forgotten what you had said on your original post.  Reboot your system and spam the F8 key.  That should allow you to get into "Safe Mode", at that point you should be able to uninstall all your graphics devices through Device Manager.  When you boot to the OS.  This should force the OS to reinstall the drivers in through default.  Beyond that, I dont know what to say without having the system in my hands.

hmm, haven't tried it yet becouse I read some posts of guys who had similar problem as mine and they said nothing had been displayed in safe mode as well as if run in normal mode. I'll let you know if it worked and thanks for help.

Problem fixed, safe mode worked in my case. I couldn't run windows in safe mode first time becouse OS wasn't shut properly (I used power button -even turning compuer off is difficult without the screen, hehe) When I found the way to turn it off I could finaly use the safe mode and enable Intel card. Thanks again Silent

Im glad something I said managed to get you up and going.  Its terribly difficult to diagnose a computer when you dont have physical contact with it.