Where can I buy a simpletech 320GB BOM No: 96200-41001-057 power adapter? which power adapter do I need to purchase??

SOURCE: Need to know where to purchase SimpleTech 96300-40001-001 12V 2A AC Adaptor

My AC adapter is fried too and I have only used this maybe a dozen times in the last year.

SOURCE: SimpleTech 320GB external hard drive power adapter

I have the same drive and it uses an Accurian AC/DC Adapter. It's output is 6.3V. Also the model number is XKD-C1500NHS66.3-12. I hope this helps.

SOURCE: Lost ac/dc adapter for a 320 GB Simpletech External Hard Drive

I have the 320GB Simpletech External Hard Drive.
The AC adapter Model number is SAWA-05-153
The output is +12V --- 1.5A

SOURCE: SimpleTech Signature Mini (320GB) unable to find on my laptop

if you hear a constant clicking return the drive it is faulty.

SOURCE: SimpleTech SimpleDrive Pininfarina 320GB Power up problem

It could be that it's internal power supply burnt out,
in which case the drive itself could still be fine.

Try opening up the external case, and removing the drive.
Once you do, plug it in to your computer directly using its SATA cables, and see if that works.

Hope I helped,
Tom