Your bad thoughts will start to go away when you get into the word of God. Start with the book of Psalms, and the book of John and form there on continue with the new testament.
Lord help this person to get into your word and understand it. Give them peace of mind and take away all their anxieties, fears, and un believe. Cover them with the blood of the lamb and protect them from all evil. Teach them thy ways Lord, I pray this in Jesus name, amen.