Stuck collective - fairly easy to recover from and practice. Get on the backside of the power curve and down you come.
I remember a few years ago a solo student in a 300 had not buckled up the passenger side seat belt. It got stuck at the base of the collective rendering it imovable. When he went to lower the collective to descend, sure enough he couldn't lower it. He eventually found out what the problem was and came home.
A stuck cyclic though? Haven't got a clue.