Windows 7 wont boot / black screen

Hi, i bought a external hard drive and really wanted to have windows on it, so i installed windows 7 with some program, ok the problem is when i start the windows just dont boot, just appears a black screen with a blicking cursor, i think it is because mbr or boot are damaged because i removed ubunto and grub recently and i fixed it with partition wizard, i eard too i can repair this with windows re but it dont work on external hard drives, is some way to use bootrec or re without windows re, plz i really need this

and some help here

Have you tried booting from the Windows 7 DVD and going to the repair console? From there you should have access to the command prompt. Try entering "BootRec.exe /fixmbr" and/or "BootRec.exe /rebuildbcd" (without quotes). Any success?

no, the dvd just deny everything related to the external hard drive

What do you mean by "deny"? It doesn't read the external hard drive? The commands are not accepted?

the commands are not accepted, when i select the external hard dryve it just says that the hard drive is not valid

OK, but you get to the command prompt? What is the exact error message?