I have been using RCT3 for some time now and never before encountered this problem. While trying to build a structure, I noticed my left shift key was not working. I tried it on raising a coaster station, nothing happened. I couldn't find any way tp troubleshoot or fix it, so if anybody here has ever experienced this problem before, it would be awesome if you'd be able to help. Thanks!

Just try again after restarting the game, on occasion games can stop reading your keyboard (or specific keys on it).