First of all, let me introduce myself as a curious amateur to data recovery. This is the first time I have had to do this, I do not work in the computer field but I have spent the past week reading on many forums, watching youtube videos and emailing support for help. I think I now know what the problem is but still need confirmation of the next steps. Help will be very much appreciated and apologies in advance if I do not add enough detail to the problem - ill try!
I have a WD Passport 500gb Hard Disk which has stopped being recognized by 'My Computer'. It is not/cannot be assigned a drive in diskmanagement and the majority of the drive is viewed as 'healthy primary partition'. I know the data is there but it is inaccessible. I have Windows 7 (64 bit) and had never had any trouble with the WD drive until I plugged it into a Macbook. I do not use Macbooks and was only intending to transfer data. However the macbook started backing up and in a panic I disconnected the hard drive. I think the hard drive is now formatted formatted for the Mac but I can't be sure as I have no idea why is won't work.
I've just testdisk to try recover the data. At first I used the 'INTEL/PC' partition analysis but nothing came of it. I next tried [EFI GPT] partition anaysis with came up with the picture below (I was surprised to see this as I read somewhere else that EFI GPT partition is for 2TB and over whereas mine is 500GB).

What are my next steps? Do I change to partition type from P Mac HFS to NTFS? Continue?
Please help! Let me know if you require any more information.
Many thanks in advance