Hey there, nortney!
No worries, you can disable and re-enable Wurst at any time, regardless of whether you're in single- or multiplayer.
By default, you can simply go to the Statistics menu and press the "Enable Wurst" button to turn it back on. However, if you've toggled off that button in the settings, the only way you can re-enable Wurst is by restarting the game.
After that, Wurst should be up and running again. If you encounter any further issues, feel free to reach out and I'll be happy to assist you.