Also please clearly state what you want; retrieve files now residing on your 1TB drive, or install windows 7 to it.
Formatting causes data to be destroyed forever; the disk will be like a new disk with nothing on it. That seems to contradict with your own statement that you want to retrieve files on the drive.
Please formulate a clear question so we may help you with your issue. It also helps to explain exactly what happened and and any error messages you may encounter. Why can't you access the data on the drive, for example?