Anyways... If its Windows XP, and MSDos and such and such... You can download and create a windows 98, or 95 Boot Disk...
Make sure your Floppy is booting on startup...
Run that, then Prompt will come.
I Believe the command is.
A:\Format C:
or
A:\Format-C
Something like that.
Lol am i even helping???
If not XP, do same thing, but no Bootup disk, just get into MS-Dos