In a laptop you need the IG to run video. Even if you had a GPU installed, the IG is used when your NOT doing high end graphics (aka looking at a Word document, reading this forum, etc.). Does the screen stay black on BOOT (when you first turn it on) or only when it starts to load Windows? If the first, then yeah you mucked up your BIOS, and either try to get a warranty assist with it or you will have to risk even more and try getting the SERVICE MANUAL for that specific model, and follow it to disassemble to get to the 'Watch Battery' used for BIOS. You would have unplugged power, pulled out the battery in the process, then pull the watch battery out and wait 15 min. put it all back together and your fine.
IF it is only in Windows you did the disable, you can start TAPPING repeatedly the F8 key when the computer powers on, then go into Safe Mode and reenable the video.