Greetings,
Welcome to the forum.
I am not a HP employee.
Did the Startup Repair option fail?
You could try to fix the Master Boot Record. Select Command Prompt at the Advanced Options screen.
Enter the following command:
bootrec /fixmbr
Then try to write a new boot sector at the command prompt if the fix command does not work:
bootrec /fixboot
This error can be caused by Windows corruption or hardware.
So you may also want to check your PC's hardware.
Start the PC, Tap "ESC".
Then select "F2".
Run system tests to verify hardware.
You may have to pull the HDD and connect it to a different PC if you need to retrieve data. The data may be available or not recoverable depending on what is happening with the HDD.
You may need to reinstall Windows if hardware tests pass. Or replace hardware and reinstall Windows if the HDD test fails (faulty memory can also cause strange things). Data recovery may not be possible if the HDD has failed or is failing.
You would have to decide how far you want to go and how much money you want to spend on data recovery.
Regards