I'm trying to find out the name of a game i used to own many years ago. It was a side scrolling game for the PC which i found used at the local waste facility; and it was a kid's game, i remember the main character was a kid using some sort of electricity gun to shoot shadow-like monsters who were controlled by the main antagonist. I think the plot was to save the kids dog? or something.

So if any of this rings a bell, just reply, and ill be able to sleep again :P

Commander Keen?

http://www.mobygames.com/game-group/commander-keen-series

More likely, it was this one:

http://www.mobygames.com/game/heart-of-darkness