do you have the microsoft windows 7 basic installation disk?
put the disk in the drive and start the computer
if the disk will run, select: "upgrade"
this repairs the operating system in many cases.
this does not erase your personal files, but sets the
operating system back to a default state. hopefully
it runs again like normal.
I cannot say that it will work %100 of the time, but
if the computer is infected it might not work...
OR have a computer shop do any of the above for you.
Making a backup of all your personal files and pictures
(etc) is very important. After the computer is able to start
up again, make backups in case of future problems.
sometimes system recovery will work, sometimes it will not. If it does not work, it is safe to use the win 7 disk...in "UPGRADE"
actually in the majority of my experiences, the HP recovery option did not work, and I wound up using the disk. But it is always worth a shot, IF the unit has the recovery option, to give it a try.