Well if they were 'moved' to the card, they should still be there.
The simplest way to try and find them would be to plug the phone into a computer via USB and look at the contents of the SD card.
It may well be that they aren't lost, but are not viewable by the app you are trying to view them through after the move. If they were moved incorrectly, or that app can't view from the SD card, this can happen.