These settings can prevent email from getting to your Inbox:
Spam folder - Check your spam folder to see if the email was incorrectly marked.
Blocked address - The sender may have been blocked by mistake.
Email filters - Check your filters to see if the email could've arrived in another folder.
Reply-to address - Make sure your reply-to address is blank.
and for account trouble
Clear your browser's cookies. Close and re-open your browser, then try signing in again. If you're having trouble signing directly into a Yahoo Mail or a different product page, try signing in to the primary Yahoo login page. Complete these steps again using a different supported browser.