How to deal with difficult 3yr old that won't talk

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I agreed to watch a 3yr old for a friend of my moms. But now she's just a bad influence on my 2 yr old. She can't talk- only grunts. She screams all the time and throws herself into things and on the floor in fits. She also attacks my daughter, I can't communicate with her whatsoever. Anyone with some tips on how I can handel her? I don't just want to give up(as she has been thrown out of daycares) I just would like some help on how to deal.