Turn out the lights. All of them.
Shut your now useless eyes and focus on silence.
Once you have blurred the noise around you, look inside. Look deep into your heart for something that is not you. When you find it, ask its name.
If it does not respond say to it, "This is MY body and I am king in it. You will speak," and then ask again. Listen closely with ears you don't have to the voice you will hear faintly.
Then pull it from its resting spot and fight it.