If you have used AutoCAD you have most likely accidently done something like this since AutoCAD enabled the ability to turn off the Command Line aka Command Window.
“Dude where did I park my Command Line..”
The Autodesk product teams receive several emails from the Autodesk Product Feedback Form. Your feedback goes to the products teams and they read them. In many cases team members respond if there is enough detail and time permitting but they can’t respond to every feedback submission, but do try to help when they can. This solution was by AutoCAD Test Development’s Cliff Young.
Help, I somehow turned off my command line at the bottom of my screen. I tried ctrl and f9....didn't work… OMG $!#**
Here is the easy Solution:
Try Ctrl + 9 (not Ctrl + F9). This should bring your command line back.
You could also try typing "commandline" at the input prompt on your AutoCAD screen.