Hi @Susie2804
this is currently an open bug.
You'll find some suggestions in this thread: https://answers.ea.com/t5/Bug-Reports/OPEN-Sim-walks-on-knees/m-p/5865847#M34356
This sounds like it may be an issue with outdated mods or custom content.
This can happen as we get updates for the games, some mods and custom content become outdated and can no longer be used. This means that you'll need to go through your mods folder to find what needs to be replaced.
Finding Problem CC
http://modthesims.info/wiki.php?title=Game_Help:Finding_Problem_Custom_Content
