Hi,
The error code will be a Smart or Disk Self Test failure - in either case, it would indicate that the Hard Drive is failing and needs to be replaced. This is also consistent with the start-up issue.
If your notebook is still under warranty, contact HP and arrange to have the drive replaced - you can check your warranty status Here.
If you live in the US, contact HP Here.
If you are in another part of the world, start Here.
If you are out of warranty and would like a guide on replacing the Hard Drive yourself, please let me know.
Regarding the data on your Hard Drive, here are a couple of options you could try.
1. One possible way to try and retrieve your files from a non-booting drive is to follow the process detailed in the link below. The Ubuntu operating system CD you create can run from the CD alone ( ie it doesn't have to install on the Hard Drive ) and I've often found it to be successful in retrieving data even from a failing Hard Drive. When you've created the CD, follow the instructions and see if you can back up your existing files - Note: You'll need to disable 'Secure Boot' and enable 'Legacy Devices' in the Bios Menu ( f10 ) before trying to boot from the Ubuntu disc.
2. Another option would be to remove the HDD, place it in an external caddy - an example is on the link below - connect this to another PC and see if you can access your files.
Regards,
DP-K