Many years of emails, but not all, have suddenly disappeared from my cell phone and PC Xfinity In Box

Hello, I use my Comcast email account on my Apple cell phone, and a windows 10 PC.  Yesterday I saw that emails in my In Box between 6/2009 and 8/2022 were gone. 13 years gone. Emails from all years before 2009 remain, and some (but not all) emails received after 8/7/22 remain. Test email sent since this happened are appearing correctly.  I have changed no settings. The approx 6700 missing items are not in trash. They disappeared from the PC and the cell phone on the same day. I have an iPad as well, and my Xfinity account there still shows all the missing emails...but i am afraid to manipulate them for fear of them disappearing too. Please, what happened to my In Box and how can I restore the missing emails? Thanks for help!!