Selective mutism is a devastating anxiety disorder that affects children. These children appear normal in every way yet in some circumstances they are silenced by this severe form of shyness.  Children who sit in utter silence, unwilling to speak in public, unable to participate in class.  They lock themselves up inside.  Their teachers don't know what to do.  Their families are sometimes blamed.   Many parents were being accused of child abuse.  But at home, the children are full of life, full of talk.  Why can't they open up to others?  What can a parent do?  ABC News with a revealing look at the paralyzing shyness known as "Mutism" that affects thousands of children away from home.This "20/20" show contains the following additional stories:Without a TraceParking TicketsThis product is manufactured on demand using DVD-R recordable media. Amazon.com's standard return policy will apply.