This happens sometimes if the VM bumps up against upper limits of memory and has to hit swap heavily for extended periods (a few minutes or more). When this happens and I type asdf at the prompt it looks like:

$ No command 'asdf' found, did you mean:
 Command 'asdfg' from package 'aoeui' (universe)
 Command 'sadf' from package 'sysstat' (main)
 Command 'sdf' from package 'sdf' (universe)
asdf: command not found

$

Note that asdf isn't showing up after $.

The obvious answer is to just kill the tab and start a new one. Still, I have to wonder if there's a way to reset a bash terminal that is misbehaving like this. I tried bash and it didn't make any difference.