|Best check easy things first. Reseat the connections to your hard drive (best unplugged and put back in firmly). If it is a SATA drive, the power plugs/sockets are sometimes a bit weak so its worth cleaning their edge connectors with a small piece of pencil earaser.|
I doubt very much a BIOS flash is necessary. These are only required under quite special circumstances, such as to suit a particular processor. If it used to work this will not be the answer and if it goes wrong your motherboard is dead.
Always pop back and let us know the outcome - thanks