No file I tried to erase one picture and somehow I erased all of my pictures that were on my camera. It now says no file. Is there a way to retrieve these pictures?

I tried downloading images from my Canon Rebel XTi digital camera into my computer and instructed the program to clear the camera upon completion. Unfortunately, the images did not transfer to the computer successfully and now I get "no file" message on the camera display. Is there a way to retrieve my photos from the camera's memory card or have I lost them for good? I tried downloading images from my Canon Rebel XTi digital camera into my computer and instructed the program to clear the camera upon completion. Unfortunately, the images did not transfer to the computer successfully and now I get "no file" message on the camera display. Is there a way to retrieve my photos from the camera's memory card or have I lost them for good?