(To OP)
You may very well have.
I know it's late and you may have reformatted and started over by now, but if not, read this post
Have you "lost" a hard drive, partition or files in your computer?
Testdisk may be able to recover your partition if you accidentally deleted it.
P.S: My original thoughts were also you did hit enter and left the floppy in the drive, but i suppose first guesses aren't always the right ones.