Step-by-step explanation:
Say that you were practising the night before so much that you lost your voice.
Say that you were gone to a match and because of the amount of screaming you did, you lost your voice.
Say that you are sick or have the flu or a soar throat (and add some coughs and sneezes just in case)
Say that you have a bad soar throat and that the doctor told you not so speak.