If the film is black, then it got too much light, if the prints are black, or too dark, then there was too little light. Looking at the film will tell the tale though. If the film is black, and no edge numbers are showing, then it got light struck, either in the camera because of light leaks, or somewhere in handling (loading or unloading or at the lab).

It sounds like it may have been cut wrong by the lab, inspecting the film will answer that too.