Hi Ginny
It is not really known what causes this however it is suspected that something has caused the 7th facial nerve to swell causing the paralysis. The following is suspected of increasing your chance of getting Bell’s palsy, Pregnancy, Diabetes, Exposure to cold temps, Upper repertory infection. There is no known treatment but steroids can help. In most cases there will be a full recovery but this can take quite a few months. In a small number of cases there may be some residual weakness of part of the face.