Couple of ways. Treatments for bell's palsy include ensuring protection for your eyes [make sure that they are kept moist and protected]. Sometimes physicians will prescribe steroids [to reduce possible swelling] or antivirals [if it is suspected that the bell's palsy was triggered by a virus]. If you suspect that you have bell's palsy, see your doctor to determine the right course of treatment.
Time and ?medication. Many cases of bell palsy resolve on their own. Medications such as steroids (prednisone, methylprednisolone, and similar) and antiviral medications such as Acyclovir may be helpful. See the american academy of neurology's article on bell palsy here: http://patients.Aan.Com/disorders/index.Cfm?Event=view&disorder_id=864.
It varies. The exact cause of bell's palsy is unknown but it may be due to a viral infection of the facial nerve. There is no universal treatment but early on anti-viral antibiotics and cortisone medications may be of benefit. In some cases surgery may be indicated. You should see an ENT specialist for further testing and advice on what is best for you.