Latitude E6430 getting a ‘No bootable device found’

My Latitude E6430 started not to boot all of a sudden. I get a message saying 'No bootable devices'. If I press F2 to check in the BIOS, the hard drive seems to be detected. I ran some diagnostic tests for the hard drive and it turned out fine. When I tried booting to a DVD, it also did not recognize the disk. What should I do next?
