Inaccessible external hard disk 320GB

I have a Seagate Free Agent external hard disk, now about 3 years old. Months ago it stopped being accessible by my computer which shows no trace of it anywhere. It contains valuable data to abt 200GB which I'm very loath to lose. Seagate can't help. I have not yet taken it to a specialist and hope to avoid having to do so. Any suggestions?

Gerry de Wit, Auckland, New Zealand

Does it show up if you plug it in to a friend's computer?

Since this has nothing to do with CCleaner I've moved it into the Hardware section of the forum.

If you plug it in and open up Disk Management, does it show up on the list?

Is it a 3.5" or a 2.5" disk?

If 3.5" make sure that both the power cord AND the USB cord are delivering power. The disk will not spin up unless both are connected well.

Have you tried taking the disk out and connecting it internally in the computer? Maybe the bridge is broken.