Okay, in the main menu go to:-
menu > Preferences > Peppermint Control Center
Select the "Window Manager" tab
Number of workspaces: 2
Did that change the number of available workspaces on the bottom panel ? .. or are you saying the workspace switcher no longer exists at all on the bottom panel ?
If the workspace switcher is missing altogether...
Right-click on a blank space on the bottom panel, and select:-
Panel > Panel Preferences
then select the "Items" tab
Check if there's already a "Workspace Switcher" item.
If not, click the "Add (+)" button .. highlight the "Workspace Switcher" item, and click the "+ Add" button you should see a workspace switcher appear on the bottom panel) .. then click the "Close" button.
Back in the Panel Preferences window, highlight the "Workspace Switcher" item and use the UP/DOWN arrow buttons to move it to where you want it on the bottom panel.
(default is just above the "Notification Area" item)