Deleting Files/HD Free Memory

Hello guys, when deleting files from a external HD the files are deleted but it doesn't change the free space on disk.. like the only way to have the space back is just formating the external HD
do I have an alternative? Do exist any other way of deleting the files and getting the space on disk back? why this happens?
Thanks guys, I really need a solution!

Victor

You have to leave the external hard drive attached to your Mac when you empty the Trash. If you empty the Trash and the drive is not attached, the files will not be removed and the space will not be freed up.

chscag said:

You have to leave the external hard drive attached to your Mac when you empty the Trash. If you empty the Trash and the drive is not attached, the files will not be removed and the space will not be freed up.

Click to expand...

ohh.. that's new for me, thanks for saving my HD

and what about the files that i've already deleted and didn't empty my trash? can I get the disk space back?

Just attach the external hard drive to your Mac and the files that were not deleted before should show up again in the Trash. You can then empty the Trash and they will be deleted properly.