Mysterious header has materialized, on far left, just above first message.  It says Last Week, and shows me ONLY those messages hat arrived then.  If I click on it, It moves to Two Weeks and the messages shift accordingly.  So, I'm forced to collect all my more recent Emails by going into Verizon website and accessing my account remotely (grrr). 

How can I get my inbox back to showing ALL my messages????????