Greetings,
Welcome to the forum.
I am not a HP employee.
"3F0" means the HDD has failed. You will have to replace the HDD. You will have to reinstall Windows 7 (W7) unless you have backup W7 images on external media.
You might be able to recover data on the failing HDD by connecting the drive (internally or using a SATA to USB HDD adapter) to a different PC as a data drive.
Regards