Hello Asebastian, there is a big possibility that you have either a boot sector virus, or a corrupt registry containing the driver for your hard drive to communicate properly ( which could be a result of the virus).

If your PC is on a network I would strongly suggest disconnecting it from the network until the problem has been resolved.

I don't think that your hard drive has been completely lost, the first thing we need to look at it is a resue attempt of your data before looking at the prospect of having to format your drive with fdisk.

I'm going to have a look around and see what I can find to see if we can access your hard drive and get it to boot up again.

Regards

Martin