What could be wrong with me?

Hi, I woke up one morning and could barely speak. I got scared since i am professor and need to talk all days. It happens to me from time to time, why is this occurring?

Hi, did you take any cold drinks? An ice-cream? Maybe, you are over protecting your throat so, when you come in contact with some irritant your voice is gone. Since, it repeats from time to time, there must be some conditions that make you more susceptible to losing voice. Once, when I was without voice the doctor asked me if I am taking any drugs or illegal drugs. Many tests must be done in order to come to some conclusion, but still doctors can stay without an answer, like in my case. In a few days I was cured, without any treatment.