WD Passport not working properly

Hello,

My WD Passport, which up to now has been working fine when plugged into my iMac has stopped showing up in the finder.

In Disk Utilities, it is shown as a connected drive but, unlike my iMac's hard drive, the number of files comes up as zero.

When the WD Passport is plugged into the iMac (USB), the hard drive can be heard whiring round and the blue light is on.

I have tried swapping USB cables and plugging the drive into 2 other Macs, but the same thing happens. I have also tried to 'repair' and 'verify' the drive within Disk Utilities but get non-informative errors.
Any suggestions of how I can access my files please?

Many thanks