Did you buy a new video card and install it in your laptop? And now you're having the problem of incompatibility?
Well, if that's the case, chances are you got a video card that is incompatible with your motherboard.
If you did no such thing described above, and your computer has been subject to dropping/hitting/bumping/falling/etc or any other type of external stress, chances are something could have come loose inside, which is causing your hardware to malfunction.
If your laptop was having overheating issues, the connections to video card might have become faulty.
In any case, this requires hardware expertise to diagnose of what the exact cause is, but even after you do figure out what exactly is causing the problem, the solutions aren't pretty. If the connections broke or become faulty, you can try to repair them, that will provide a temporary solution but might become undone in the future. If you need to replace the videocard, unless the chip can be taken out of the motherboard freely and replaced, the replacement will require the whole motherboard to be replaced along with majority of the hardware that comes with it. In such a case it would be easier to just buy a new laptop.
Alright, I know this was lengthy and blocky, so TLDR:
- if you got new GPU, you got the wrong one
- if you didn't get new GPU, you have a hardware problem, best solved by replacing the laptop.