Seems like ^L usually clears things up when this happens.
But terminal corruption used to be far more common (line noise, etc...) and bash has a built-in escape for this. Ctrl-L (chosen for the analogy with form-feed/"vertical tab" on a printer) will blank the screen and redraw your current edit environment at the top.
BTW, it's the readline library that handles the Ctrl-L key binding to clear the screen rather than bash per se.
$ bind -p | grep '\\C-l'
"\C-l": clear-screen
$