If these procedures do not work, it suggests that your internal HDD is faulty or the cable may need to be replaced.
If you external boot drive functions, install it in your MBP and see if that will solve the problem.
it means that the HD and the software can't find each other, the following article tells how to troubleshoot the issue:
hopefully you have backup of your data since this sometimes means the HD is crashing.
if the articles don't resolve the issue i would take it to apple store or service provider for service. the following link tells how to find one close to you: