how could a drive that's currently running an OS like windows format itself while working mate ? it's like asking someone to eat himself entirely

the simplest solution if you don't want to use any CD nor floppy is this. Boot the PC, then after the BIOS screen, press "F8" until a menu appears (the one where you can also choose "safe mode" if you see what i mean).
On this menu, select "command prompt" , then you're done... once you have the prompt, type in format c:

Tis the same as what i said above, but you don't need the CD then. But careful mate, if you don't have any Windows CD, how will you reinstall your OS after formatting ?