OS Setup using a flash drive

I have a notebook Fujitsu s7211. Recently my DVD Rome is out of order (cannot read DVDs). I recently needed to install OS (Windows 7) and I thought of doing that using a flash drive of 8GB. In order to make my flash drive Bootable I used DOS "diskpart" and tried to create a primary partition. Everything was going fine. When I made the command "format fs=NTFS" and tried to "assign" something went wrong and it did not work. Now the problem is that my windows cannot recognize my Pen drive. When I am inserting it and trying go inside it says, "please insert a disk into Removable disk (j)". I tried to format it but it says, "Windows was unable to complete the format". I also tried it using DOS however it did not work. I don’t know what to do. Can you help me with this problem??
