My inbox messages have been deleted automatically.

For the past few days my inbox was looking different.  At first I thought it was just an issue with my internet connection and my inbox not loading correctly.  However now i am noticing I have no old messages in my inbox.  I have tried different browsers even the google app and nothing.  Last night I checked my email and noticed that emails I viewed a few days ago are no longer there as well.  Why is that happening?  Please help