Around 14 months ago, I bought an HP notebook for my relative. They need it for college. It works absolutely fine until about a few days ago. And then the screen switches off. But the notebook continues to work because music is still playing. But what is quite strange is that it is not possible to restart.

Normally you would hold the power button and in a few seconds computer will restart. But not in this case.  I have never seen anything like that and typically when you hold the power button, the motherboard will detect this and force power off. Initially, I thought to update firmware but then my relative gave me the reasonable idea to search the internet.