Desktop

I assume you disabled the on-board graphics in BIOS setup. Simplest fix is to reset BIOS. Default setting should be enabled.

Look for a BIOS reset jumper on motherboard. Alternately, remove coin cell battery for about 5 minutes and then re-insert.

We can't give you any specifics because you did not provide model number. If the above doesn't help, add a comment with more information.

Dalton

Just to expand a bit to Dalton's answer if you do remove the Battery make sure that the unit is unplugged!

I've seen far too many M'Boards reduced to junk because the battery was dropped onto a live M'Board and produced a short circuit.

But there should be a Jumper on the M'Board to clear the BIOS this is generally a Yellow Jumper on Modern M'Boards but look in the manual that came with the computer to identify the right jumper and if there is one fitted. There should be 3 pins and pins 1 & 2 are connected by the jumper and you need to pull off the jumper and close pins 2 & 3 to clear the BIOS. Once this is done you'll have to reset the Date/Time and all the other things in BIOS but if you have the option after you reset the time & date you can run quite safely with "Performance Defaults" and after that is done you'll never need to go into BIOS again.

Col

this is a wild flyer but maybe you hit the keyboard combination (on this laptop?) to switch video outputs. you saying you get video on boot but then connect get signal to external monitor or on display? i would hunt keyboard and manual for changing video output