@Anonymous:
I just downloaded the free "Hobbyist/Student" license and even through I've gone through the steps you describe to create a new sketch, still Sketch and all of the associat0ed tools do not appear. Do I need to uninstall/reinstall or is this a known bug? Please note however, I did also try the other steps you and others mention about clicking on the plane I wish to draw on, creating a line, clicking on Finish Sketch, reset the toolbars and every other "workaround" or suggestion listed in all 24 replies. None worked. As someone who actually worked for AD many years ago in Tech Support in the 90s, I'm not 100% new to CAD as a whole, just very rusty. That said, this makes the experience of getting back into it quite unneccessarily frustrating and a very big waste of time.
Note: this is a clean install on a moderately high end brand new laptop - certainly well above minimum specs in all regards.
I have not tried (being an absolute beginner to the software) opening an existing sketch, but as the steps for creating a new sketch are quite simple, I'm fairly convinced it's not that I'm somehow creating a new sketch incorrectly and no warning or other messages appeared.
Admittedly, it's difficult to get started with the software without this option...
Any info much appreciated!