How to get back the 'Add ' menu after performing any other action? I would like to know how I can get back the 'Add ' menu which disappears after performing any action.

I tried F9 key, F6 key and T key which I knew after some Googling but they didn't dork.

I'm using Blender 2.80.
unfortunately not, you can just delete the object and re-add it though!