deleted files from an external drive not showing in trash

Hi, would be very grateful for help.

I've been transferring TV shows that I recorded onto DVD years ago, to hard drive in MP4 format. I have an iMac in the basement connected to two TV's so I can watch. I have been ripping the DVD's to my Mac mini in the office and then transferring them to an external drive connected to the iMac in the basement.

From the office I was connected to the iMac and I accidentally deleted a folder on the external drive. I immediately aborted when I realized files were being deleted, you know how it counts down the files. The folder I actually wanted to delete had a similar name but with no files.

No problem I thought, I went to trash on the iMac but those MP4 files were not there. Now, they are large 2-5gb each. But, the other day I deleted a similar large file but I did that directly from the iMac and not remotely from the Mac mini in the office. But that file was there in trash but none of the files that I had deleted remotely! I don't know if this makes a difference. but even when I go down to the iMac and look in trash directly I don't see those files.

I would appreciate any help, those files must be still on that disk and I haven't loaded more to overwrite them.

I hope I haven't confused by explaining the two computers but it seems that it could be relevant.

Many thanks