Attach it to your computer, open an elevated command prompt box (right click run as admin), type the word diskpart and hit return, then type list disk and hit return again.
That should show a list of all attached drives internal and external.
*Carefully* select the drive number that is your 2TB Seagate Expansion Drive and type select disk n (where n is the number for the Seagate)
That will shift the focus to that drive and then you can type clean and hit return. Now it should show up in disk management and you can initialize it as an MBR drive and then format in NTFS. If there are important files on it you *may* be able to recover some with a lot of work, although it is by no means guaranteed (so hopefully you have a backup of the data).
HERE is some more detail on other diskpart commands and the syntax.
If diskpart fails to recognize it there is a different more labor intensive task ahead.