No. Nobody has ever been stuck in hypnosis.
It's a common misconception that when you in a hypnotic trance you are asleep and only able to wake up when your hypnotist tells you to. The reality is quite the opposite. You are not asleep when you under hypnosis. Hypnosis is a state of deep relaxation coupled with an intense focus on the hypnotist's words and actions. You could wake yourself up at any time but you won't want to.
However if, for example, the hypnotist walked out of the room and didn't come back you would eventually realise that they had gone and you would "wake up" from your hypnotic trance quite naturally. Remember that you hypnotise you; the hypnotist is just a guide and you remain fully in control through the entire experience.
The same is true when you are using a self-hypnosis audio. If your MP3 player suddenly broke down, you would soon notice that the hypnotist's voice had stopped and you would wake up. Most good quality self-hypnosis audio tracks will also remind you as you enter your hypnotic trance that you will be able to exit hypnosis quickly and easily if anything occurs that requires your attention.
Remember, the primary tool in hypnosis is your subconscious. The primary function of your subconscious is to keep you safe. You cannot, and will not, get stuck in hypnosis.