i am going to ease your mind

what you have is an extreme coincidence! The action of unplugging the devices while the computer is off or on will have no ill effect.
Im going to hazard a guess, that while you were moving it around something has come loose, so your best bet is to take off the side panel, and check the cables to the hard drive and then trace them back to the motherboard and check they are plugged in securely.
Then boot the computer, if it boots then go have a beer, or it doesnt, restart and then enter the bios, f1, f2 or delete are common command but it will say somewhere on the boot screen.
once in the bios find the boot order and see if there is a HDD recognised, if it is move it to the top of the boot list and retry. that should sort things.
if it doesnt push the computer on the floor, and sit the dog on top of it.. then have a beer