It depends on the model.
Some have a bevel that's just snapped into place. Usually there's screws at the corners, which are covered by rubber 'dots' that disguise the screw holes.
Now, there's the possibility that the signal cable (usually a ZIF, or Zero Insertion Force) is either coming loose, or is damaged. If it's under warranty, I strongly advise letting an authorized tech do it.
If not, check the connection very carefully. The actual connection is very fragile, you break that, and you're shelling out hundreds for a new display unit. Usually just a very small amount of force on a plate will open the cable brace, and it just slides out. NOTE - when putting it back in, get it straight in, don't force it, or you're going to be screwing/unscrewing a lot.
The other end is connected to the system board inside the laptop. It's not very common that that end comes out, and getting in there would require removing the keyboard, keyboard bezel, etc., depending on which model you have.
If you need part numbers, look for an HP web site called Partsurfer. It will have their part numbers. Then do a Google on the part number, and you may find it cheaper on the Web.
Good luck. But first, check the external video on an external monitor, to see if the problem happens there as well (should eliminate the system board as a possibility)