|As there is no DOS Mode in Windows 7 you cant get out of it. DOS died with Windows 98. What you have is a Command Prompt. To exit the Command Prompt type Exit.|
If it went straight to a Command Prompt from boot up then you are probably in Ssfe Mode in which case you need to re-boot.
The other possibility is that you are not actually booting from the hard disk but from a disk in the CD Drive.
Although what all this has to do with programming I have no idea. It would be better in the Windows 7 forum.