Speaking

слушаться [no Pf.]: Ng языкn не слушается N's tongue won't obey, N is unable to speak
заплетаться [no Pf.]: у Ng языкn заплетается N is incoherent, N is unable to speak (lit. "N's tongue is tied in knots")
NB The above expression is often used when describing the speech of someone who is drunk, or otherwise unable to speak normally.
прилипать/прилипнуть: у Ng языкn прилип к гортаниd N is struck dumb (lit. "N's tongue has stuck to his larynx")
NB The above expression is used to describe a state of fear or embarrassment.