Did you try to connect the external DVD writer to a different working windows computer? such as a desktop PC? If it doesn't work, or doesn't have a disc in it as neem says, it could throw an error. Also, if the DVD writer doesn't work on a different computer, you might try cleaning it and using isopropyl alcohol to clean the laser lens. If it still doesn't work on another computer, that DVD writer could be bad. How long have you had it? Is it brand new or several years old. If so, it simply might be time to replace it with a new working unit. They can be had on newegg.com or amazon for about $35 US.
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