We will be taking a lot of assumptions in this question. Assuming that Landan did not accidentally drop his laptop, as a technician, what I would want to check first is the BIOS settings. There are a couple of issues that can cause this error. These issues may include a boot sector virus that erased the whole hard drive, a bad windows installation, or even a loose cable. Before I check on the BIOS settings, I would request him to unplug any external hard disks. He might have been watching his movies from the hard disk and the disk being connected might be the one causing the error. A wrong boot order in the BIOS settings may be giving priority to another boot source disk like the external hard disk mentioned. I should be able to take Landan through steps that he needs to take to make his hard disk priority. I would also check for corrupt sectors by running the inbuilt CHKDSK tool. If these options don’t work, I would consider checking the hardware itself for further diagnostics.