If a tooth is knocked out: 

Immediately call a dentist for an emergency appointment. It is important to see your dentist within an hour for the best chance of the tooth surviving the trauma. Handle the tooth by the crown (the top), not by the root (the pointed part on the bottom). Touching the root of the tooth can damage cells that are necessary to reattach the tooth to the bone. Gently rinse the tooth in water to remove dirt. Do not scrub the tooth! It is important not to let the tooth dry out.  The tooth could be placed in your mouth between the cheek and gum. It could also be wrapped in a clean cloth or gauze and immerse it in milk or saline solution (the solution used for contacts). If a baby tooth is knocked out, the tooth should not be replanted. The patient should be seen as soon as possible to make sure there are no remaining pieces of the tooth.

If a tooth is pushed out of position:

If your tooth is loosened and pushed out of position, call your dentist right away for an emergency appointment. In the meantime, attempt to reposition it to its normal alignment using very light finger pressure—but don’t force it!

Chipped or fractured tooth:

Chipped teeth are minor fractures. Moderate fractures include damage to the enamel, tissue, and/or pulp. Severe fractures usually mean that a tooth has been traumatized to the point that it cannot be recovered.

If you fracture a tooth, rinse your mouth with warm water and use an ice pack or cold compress to reduce swelling. Take ibuprofen, not aspirin, for pain. Your dentist can smooth out minor fractures with a sandpaper disc. For moderate or severe fractures alternative restorative procedures may be needed to fix the tooth. Never attempt to glue a natural tooth or part of a natural tooth back into place!

Reference: Academy of General Dentistry