Hi there Mero4g,
What does the drive make? Does it even spin up?
You can start with something simple as just attaching it with a different USB cable.
In case the issue persists, you need to go to Disk Management and see whether and how is the drive recognized over there.
If it is, but has damaged partitions and/or file system, you will need to use some data recovery software in order to retrieve the data stored on it:
http://www.tomshardware.co.uk/forum/id-1644496/lost-data-recovery.html
If it is not, then there is something wrong with the enclosure or the HDD itself.
In that case you can:
- RMA the drive if it is under warranty.
- Contact a data recovery company in case the data stored on it is really important.
- Some users take the drive out of the enclosure in similar cases, in order to attach it internally via SATA. Keep in mind that this may not work due to multiple reasons.(proprietary connectors, hardware encryption, etc.)
Let us know how this goes,
D_Know_WD