Gday @Mudshark ,
First can i ask you to reflect the "Edition" of Zorin OS your using in your profile please, this saves asking in any future help you may need.
Can you remember changing or any app's installed prior to this happening?
I use Zorin OS Core, i only seem to get the side panel after i click the workspace taskbar icon ( next to the start button).
To change workspaces i use Ctrl+Alt+ Arrows.