Adult Sim suddenly wearing Toddler Sim's outfit

You can just upload the save game as is if it's not too big.

but to create a zip file follow these instructions: 

https://support.microsoft.com/en-us/windows/zip-and-unzip-files-8d28fa72-f2f9-712f-67df-f80cf89fd4e5 

Your saves can be found in the following folder: Documents\Electronic Arts\The Sims 4\saves