I accidently grew a toddler up is there anyway to make them a toddler again? THANKS<3

Get the inSIMenator from the homepage here at MTS2. You will be delighted at how effective and easy to use it is. It is a robust and well documented product, and kept up-to-date.
There's 3 to chose from, but they all work fine.
Once it's installed in your download folder, start your game, enter the lot with the child, left click on an empty part of the lot, and the machine appears. Just select the child in the usual way, then click on the blue section of the machine to bring up the options.