What causes someone who knows how to speak to go mute?

Social Phobia: I understand your discomfort. Your family experiences of childhood may have caused stress and holding of your feelings inside yourself , and may have caused low self-esteem. Withdrawal , and later social phobia. Social phobia may have increased comparing yourself to others. Please see a therapist to understand and improve social phobia.

Multiple ways: There are multiple possible causes for someone who knows how to speak, to go mute. One would be a tia, or more likely a full stroke; damage to vocal cords is another. Also someone can have an extreme psychological trauma and not be able to speak because of that. People can also be mute with some psychoses and extreme depressions.

Fear, anxiety parano: Fear, anxiety or paranoia can do this. People in the soviet union often would not speak in public due to fear of the gulags. People with bipolar disorder or schizophrenia can develop catatonic mutism. People with severe social anxiety disorder can become mute. Autism can cause mutism and I have seen it in dissociative disorders, including in severe depersonalization disorder and in did(mpd).

Speech vs language: This can indicate stroke. Aphasia is inability to either produce speech (expressive aphasia) or understand speech (receptive). Dysarthria is speech sounding garbled or otherwise wrong; anarthria is inability to form any verbal expression. If it's sudden onset of speech loss, this may be an emergency/ stroke; get checked out at the best stroke hospital near you.