When you used TestDisk, the drive was mounted read-only, right? If it's mounted read-write then that can overwrite some of the deleted data you want to recover.
Also here's a suggestion. Before you start using the drive again, back up the whole partition to another drive (which can fit it of course).
That way, if you ever in the future find a way to recover deleted files, you still have the drive image to work on. Low-level copying utilities like dd copy everything exactly as it is present on the disk, independent of the state of the filesystem (unlike commands like cp). This includes copying deleted files, corrupt date, filesystem errors, etc.
sudo dd if=/dev/sdb1 of=/media/backup/sdb1.img # assuming sdb1 is the partition which you accidentally deleted files from
Also did you try PhotoRec, or is that done automatically by TestDisk. TestDisk, if I remember correctly, is used for fixing corrupt partitions with damaged filesystems, etc, whereas PhotoRec is desiged to recover deleted files on a working filesystem.