Hello. The answer depends on what is wrong with it, which we might be able to determine with more information. Such as
o Did it ever work? Is there data on it that you need?
o Does it have a separate power supply? Is that supply putting out voltage?
o Do any lights not light up that used to? Do you hear spinning disk or not?
o What interface is it? USB, USB 3.0, FireWire, eSATA?
o Does it work on another machine?
o How does it not work? Does it fail to mount, or appear empty, or say that it needs to be formatted each time you connect it?
More details give us more information. The generic answer is for people who have data on their drives and need to recover it after the drive went soft-flaky (no smoke, the motor turns, the PC sees that a drive was attached). Then we say try a tool like Easeus Partition Recovery as the first level of test, and then any of a number of sector-by-sector data recovery tools if that doesn't find your data.