Windows 7: Deleted old win 7 from c drive, now new win 7 won't boot

1.Put the Windows 7 installation disc in the disc drive, and then start your computer.
2.Press any key if you are prompted to boot from the DVD.
3.Select a language, a time, a currency, a keyboard or an input method, and then click Next.
4.At the next screen click on Repair your computer (do not click on Install now).
5.Next screen select Use Recovery Tools at the top of the box. (Ignore the message about the operating system not being listed. If it is listed select it). Click on Next.
6.In the System Recovery Options box, click Command Prompt and a box will open.
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Then follow this to get the disk set to active. Each command you type at the diskpart prompt will receive confirmation.
7. At the prompt type diskpart Hit Enter and wait for DISKPART > to appear.
8. Then type list disk Hit Enter (It will show a list of the disks, 0 through to how many disks are installed).
9. Now type select disk # (the '#' represents the number of the disk e.g. you would type select disk 3 to edit disk number 3) Hit Enter
10. Now type list partition Hit Enter
11. Select which partition to use by typing select partition # (you need to select the partition that the operating system you are trying to repair is installed on, again replace the # with the appropriate number).
12. Now type active Hit Enter (typing inactive will reverse the setting)
13. Now type exit Hit Enter then type exit again to close the command prompt.

Then remove the windows disc and click on Restart at the bottom of the System Recovery Options box.
If it still fails to boot you will have to go back and repeat instructions 1 through to 6 and click on Startup Repair under System Recovery Options and let it run.
If that also fails to get it booting you will have to go back again through the instructions 1 to 6 and select the Command Prompt. Then follow this next stage, type each command as follows, hitting Enter after each line.
Bootrec.exe /FixMbr
Bootrec.exe /FixBoot
Bootrec.exe /RebuildBcd
Type exit to close the box and click on Restart.
That should do the trick! However if you still can't start Windows, then follow step 1 to 6 again and type this command.
Bootsect.exe /nt60 all /force
Type exit to close the box and click on Restart.
Make sure you type all the command lines exactly as written including any spaces between characters, all can be typed in lower case.

is it a problem if i am using a usb disk instead of a dvd

usb is the boot device and i have followed all the instructions, nothing seems to work,

when i used the export.... command as suggested in the bootrec.exe tool, it says that a device attached to the comp is not working.....