transcend disk ina ukubwa gani?
unatumia windows yipi? Xp 7 au 8?
Is it a new external or old (umeisha itumia mara nyingi?
If its new , after connecting, try to go to the device manager, ( right click on my computer, manage,storage, disc management.
There you could see the new drive, you could format there by right clicking. They check if it works.
If its old and suddenly stopped working, it could be due to bad sectors in hdd. Try chkdsk command of windows. in command prompt, "chkdsk 😀rive /r"
No quotes, in place of drive, you should provide the drive letter of your disc.
Good luck 🙂