Possibly, it depends on how you deleted them and whether or not you used the memory card afterwards. If you formatted the disk you can try "unformating" it, which is really a program trying to recover the old data that may not have been overwritten, with a separate utility.
If you just deleted each file by accident I would give a program like http://download.cnet.com/Data-Recovery/3000-2094_4-10664893.html?tag=mncol a shot.
Whatever you do don't write to the card!