Hard Drive Lost space

OK so I have an external hard drive with some incredible magic disappearing space. Here is what I did.

I use this FAT32 hard drive to transfer files from mac to pc and vice versa.

I had about 96 gigs of stuff I wanted to delete and I moved them to the trash bin on the mac. I tried to delete, it would only let me delete about 60 gigs reset was locked or something.

I gave up on the mac cause im better with the pc and went to the H:\.trashes and found the files. (External is H:\ obviously.)

there was 36 gigs left of stuff which i tried to delete via recycle bin. While it was deleting the 96,000 files, i accidently hit the upper-right hand red "X" to close the dialogue box, and it closed. Now my hard drive is missing about 30 gigs of unallocated space. Is there any way to see the files that OBVIOUSLY and due to my own stupidity are still there?
Thanks in advance for any help on this one. You guys are the best.