You say you cannot get a DOS prompt. Is that because you are trying to use the SAFEMODE to try and recover the password?
I use a linux floppy disk that boots into Linux and allows you to change the Administrator Password.
Therefore if you have a floppy disk or even a USB drive which has floppy drive capabilities then you can use a program called RAWWRITE to put the image onto the floppy.
It is quite easy to use and certainly gets you out of a bind when the local administrator password has been forgotten (or an over zealous IT-Manager has changed it to prevent the normal user accessing the workstation).
You can do a search on the web for PASSWORD RESETTER, however if you do not have any success then sned me a message and i will forward you the .bin file i use.