How to stop being shy ... ?

This extreme shyness is making me feel out of place , It all started when my father died 4 years ago don't know what happend to me really before it happen I talk like any average person . This shyness of mine is also making me struggle in school too , I talk to low , I can't do presentations right or I walk away from it due to me being scared to death , I don't know what to say a girl etc. I just wan't this curse to be banished . Please helps !!!