Welcome to Android Central! As Miss_rosieannie implies, it's important to be aware of which calendar account you're entering events to, and to make sure that calendar account is being synced and displayed. I would also add that in general, you should strongly consider adding your calendar events to an account that gets synced automatically somewhere (like your Google account's calendar). If you only use the local Phone account, then you may lose all of that information if something happens to the phone, since it doesn't get synced anywhere automatically.