How to install windows 7 from USB stick via CMD.

1. Go To Run--- Type DISKPART.
2.Type LIST DISK.
 A list will be shown....... e.g. DISK 0 ,DISK 1, DISK2
 mark your pendrive disk .....
you can know your pendrive by seeing the size.
3.Type SELECT DISK 1/2/3 ........depending what it shows for your pen-drive in your system. 
4.Type CLEAN.
5.Type CREATE PARTITION=PRIMARY.
6.Type SELECT PARTITION=1.
7.Type FORMAT FS=NTFS.

wait for  some minutes..

8. Type ACTIVE.
9. Type ASSIGN.
10.Type EXIT.
Now Copy all the files from windows 7 dvd to your USB Stick.

One more step,now that you have copied all the files,go to the boot folder and copy bootsect.exe and paste it in the root of your pen-drive.

NOTE: Diskpart works only in Vista and Windows-7.