if you deleted the files by accident, there are recovery programs that can recover data. don\'t write on the drive as you will not be able to recover that data in those areas.
is the drive making funny noises? clicking? the dive might be failing. I hear putting the drive is the freezer, then plugging it in, can make an unreadable drive start working? copy files to another dive asap.
is the dive being recognized by the computer?
plug the dive into another computer and see if you can recover or see the drove/files.
reboot, try an different usb port. check connections again.
when you plug the drive into the computer, does the computer ask you to reformat? your drive may be corrupted and has lost the partition. there are recovery programs that can fix partitions on the drive.
good luck