Somehow the GNOME Terminal (Ubuntu 16.04, bash) cursor changed from the standard line cursor to a useless block cursor.
I've encountered this problem before and there was a keyboard shortcut that fixed it, but I can't remember what it was.
Based on what I've gathered from other forum entries I might have entered an input/insert mode. When I press alt + (arrow keys, Up-Down-Right-Left) I get A-B-C-D.
I've tried simply pressing the insert key (laptop keyboard, HP Notebook) to no effect.
To summarise: I have a block cursor. I would like to have the standard line cursor.