Missing eMails from Inbox

All emails, both read and unread, except for those received within the last 4 hours, are missing from my inbox. This issue exists in both my apple mail client and when using the currently / yahoo mail web mail client.  Previously I had lost a group of emails for approximately a 6 month period from April 2019 to November 2019.  Now everything is gone prior to 0400hrs PST today.  Thank you!