Originally Posted by daoswald

If using the left shifter, which controls the front derailleur resulted in messing up your chain, either the shifter or the derailleur was already messed up, and the chain was a victim of the poor mechanical condition of your bike. It's hard to imagine a situation where a damaged chain would necessitate getting a new bike. But if the bike is cheap enough, with lousy components, and a lousy cheap frame, then having malfunctioning components might be enough reason to get a new bike. I've had a few times where a neighbor will bring some hand-me-down big-box-store bike over and ask if I can help fix it. Some of those times the answer has been, "You need a new shifter, and I don't think you're going to find this no-name thing in a bike store, so you'll probably need to either settle for this being a one-speed bike, or buy a different bike."

It's possible that your bike is in that category.