When I accidentally deleted my anime folder, I used software called Pandora Recovery to get most of it back. However, not all of it was recoverable, maybe some 85%. The rest turned out as null files with zero size.

What David said about another computer would likely help immeasurable if it's your system drive or another equally actively used, but if it's an archive drive seeing no use except when you specifically save something there, it shouldn't make any difference. As long as you make absolutely no changes to the drive after the accident. My own 15% loss was likely due to the fact that despite deleting some 75GB of downloaded anime, I didn't immediately pay any attention to it and, if memory serves, downloaded something onto the drive before taking action to recover the stuff.

If you already tried two programs and it didn't work, you are probably out of luck. I imagine the all recovery softwares work in a uniform manner.