Speaking

слџшаться [no Pf.]: Ng язІкn не слџшается N's tongue won't obey, N is unable to speak
заплетђться [no Pf.]: у Ng язІкn заплетђется 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.
прилипђть/прилќпнуть: у Ng язІкn прилќп к гортђниd 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.