vim hang

To unfreeze Vim Press
CTRL + q

This happened because you might have accidentally pressed 
CTRL + s (Software Control Flow)


XOFF/XON representations in ASCII
Code	Meaning	               ASCII  Dec	Hex	Keyboard
XOFF	Pause   transmission   DC3	  19	13	CTRL + s
XON	    Resume  transmission   DC1	  17	11	CTRL + q
Man From Earth