The date and time will

Open your battery door. Notice inside that there's a little slide door inside labeled CR1220. Pry open this little slide door and remove and reinsert the encased watch battery (this battery powers the camera's clock). Removing and reinserting might fix it temporarily, but more than likely this battery is getting very low. Recommend going to your local drugstore's battery section and buying a replacement CR1220 battery. They're very common and inexpensive (a few bucks).