I got a pretty deep cut on my toung and it won't stop bleeding. How do I make it stop?

Go to the ER. I recommend that you seek urgent care and go to the emergency room to be seen by a physician as soon as possible.
Tea bag. Try applying gentle pressure with a tea bag. The tannic acid may help. If bleeding not stopped in half hour, see Dentist or Oral Surgeon for emergency care. As tonge heals avoid anything too hard or chewy, too cold or too hot, and avoid overly spiced food.