The first several days after the onset are crucial for the future recovery. Visit your doctor at once and start with medication. Take lots of rest and stay calm. There is no way to "switch back" your facial nerve at once. It will take at least 3-5 weeks.
Be patient. Bell's palsy is not a disease, but rather a functional disorder. Like a broken leg or the moved lawn: it can not re-grow back overnight. So is the facial nerve. If the damage was severe, it may take up to 2-3 months to see improvements.