ALL INBOX emails have disappeared!

I have a had Comcast email address for over 20 years, I use my MacBook to get my mail, using Comcast email, the 'Mail' version  on my laptop is 15.0. I noticed a couple weeks ago that all Inbox items over 30 days had disappeared. Then today, literally as I was reading new emails that had just come in... they ALL DISAPPEARED!  I did not delete or move them, I checked 'auto forwarding' which wasn't the issue. I logged on to Xfinity email online to see if the emails are still there... the only ones that still show are automated emails from Xfinity. PLEASE HELP! I need to get these emails back! And I need to receive new emails asap!