Invalid Partition Drive

I have a Dell Latitude E5440. I was setting a password for system and administrator using features on boot-up F2. When I exited, I got the message "Invalid Partition Table." I did nothing other than set passwords. I can't figure out what happened to get the invalid partition table. Can someone help me re-establish the partition so Windows 8 will boot again?

As a noobie, I will need step by step directions.

Thank you for any assistance to solve this problem.

Kitty Hawk

Dell Technician told me the HD was bad and they are sending a new one as a replacement. Thank you all for looking over this question.

Update: Still have the problem after installing a new solid state drive.

Does anyone know how to get to the "Repair Your Computer" screen on boot-up? I understand that it can be fixed there. I've tried finding it with F2, F5, F8, F11, and F12. No success, unless I somehow overlooked it.