What is the exact problem?
u can run cmd from inside windows(start>run>cmd), but if U can't get to windows, and you want to do some scans, or try to fix something, then U do it with Safe mode, but if that doesn't work too, then you go to Recovery console (I think that is what U want)
Boot from cd (go to bios by pressing F2 or Del, etc.)
Change boot order for the cdrom to boot first.
Save and restart.
Press R to access Recovery console.
Type 1 and press enter
Press enter if you don't have password or enter your password.
Welcome to Recovery console! (cmd)
U can rename, copy, move,delete,find,change,replace, scan, ...a bunch of things if you know how to use it correctly.
If not, write what U actually want to do and what the problem is.