Can you hear the HDD spin up when you start the laptop? If not and even if you can, then the HDD may have failed and will have to be replaced.
Here is a link to service manual for your laptop. Scroll to p.39 to view the necessary pre-requisite steps and then the procedure to remove the HDD.
Use this to initially check that the HDD is firmly connected.
If it is, you can try and re-seat the HDD and see if this solves the problem, (remove and re-insert the HDD).
If this doesn't work then you could remove the HDD and install it in a desktop computer and check if it is recognized and works there.
If it does then there is a problem with the motherboard in the laptop.
If it doesn't then the problem is with the HDD.