Hi,

The first question is whether you have a full Windows installation disk or not. If your machine is fairly recent and is a "brand name" then this is probably not the case and you will have some sort of "recovery disk" or partition.

In that situation you should follow the manufacturer's recovery instructions.

However, the first thing to try is hit the F8 key on startup and look for the option: "Boot using last known good configuration".......... believe it or not that sometimes works, and is a hell of a lot easier that using the Recovery Console or a Repair Install.

The first thing you need to consider is why this has happened? Frequently it is a symptom of a failing hard drive, so there is no point in doing anything more than recovering your data and starting afresh with a replacement drive.

You should find links to HDD maufacturer's diagnostics tools here:

http://www.tacktech.com/display.cfm?ttid=287

Get the one appropriate to your drive and run it first. If it passes then continue with your repair process.

Even if the F8 option works, you should still run the disk diagnostics.