Hi… two things:
-
You can appeal your silence/mute here:
Contact Support - Blizzard Support
Click on the Contact Us button at the bottom. -
There is currently a bug that prevents players that are muted in a Blizzard game to play Diablo III… it won’t let you join a game nor start a new one until your silence ends.
See: Silenced players not able to play for some background information… there is currently no workaround. You should be able to play again when your silence ends.