Hi Hussar
Well I knew there must be some downside to living in that part of the world!
I had a similar problem with a digital camera, tried everything but to no avail. I finally found and eventually bought, 'Digital Photo Recovery' software at
Digital Photo Recovery software for Digital Picture Recovery, Digital Image Recovery and Digital Media Recovery I have to say that I have no connection with this company but simply found that this software worked in my case. It cost me around GBP30. It is very slow, and to scan a hard drive will take a LONG time, but it was worth its weight in gold in scanning a memory stick. You can also use it to recover other deleted files if required.
If you search on the web for 'digital photo recovery software' many of the vendors will allow a download and free trial. The free trial will usually allow you to scan the memory, so that you can at least see if it will work in your case, but then not allow saving of the recovered files until you have purchased. I suggest trying free versions until you find one which works for you. It will take some time, but it depends how much you want those pictures back...........................! I just found that the above seemed to work for me.
If it was easily removable memory I would say, 'Send it to me and I'll see what I can do,' but a hard drive ....................
All the best with it.