Proteus oscilloscope not showing in simulation if you exit it during simulation. Oscilloscope do not appear on starting simulation automatically. basically you have exit oscilloscope window.

Recover hidden Digital Oscilloscope window in simulation
you should restart simulation if already not. Then go to Debug in Main Menu. and at bottom you will find Digital Oscilloscope Check it. then Oscilloscope will appear again.

Related Posts:
Proteus visual designer for raspberry pi and Arduino