When you power-on your computer, can you press the indicated key to "enter BIOS setup", or something similar?
One of the options might be to run the HP Hardware Diagnostics, to see if you have hardware problem.
If the hardware is OK, then your copy of Windows is messed-up.
It is probable that all your personal files on the disk-drive have not been damaged.
A computer technician can make a "backup" copy of your files to an external disk-drive,.
Then, there are several options on how to reinstall Windows.