Multitrack and Waveform Buttons have disappeared

You seemed to have disabled the "Tools" asset. Just go to the "Window" dropdown menu and make sure there's a checkmark next to "Tools." If it's checked and you still can't see it, you may have collapsed that asset, in which case you need to do as the other responder suggested and click on the black line at the top of the screen and pull down to make it reappear.

I've done this too many times. Here's what you do. Go to the top left of your session with your mouse cursor and you'll see a hand icon. Left-click, hold it down and drag the hand icon down until you see the Waveform and Multitrack icons reappear. It's that simple! Done. No need to restart anything!

So where did you get the screen-grab from? they look fine in there... 😉

Either delete all your preferences and restart Audition - the easy way to do this is to close Audition, and restart it with the Shift key held down - or simply uninstall and reinstall Audition. If a reinstall on its own doesn't work, then definitely you've got a preferences fault, so go for the preference deletion.