Outlook classic missing important folders and sync issues

Hello, so I have a customer who has Outlook classic on Windows 11.. In December, he checked email and all his folders with important files were gone... No backup.. He tried a few things and now system restore, repair, recovery, scanpst.exe modify office, new profile, new account, all won't work..I finally got all his folders back but uncovering a few .pst data files.. But am missing all emails in folders from 8/25 to 12/25(important emails) and other folders only go up to 2024, nothing since... Extra info: had Verizon. Net email, being used in Outlook...originally looks like he had POP, Microsoft exchange on one PC (which only saves locally),imap on other one using Outlook for email on both.. I've done the generate password from AOL .. Things send and receive sporadically in inbox and outbox..I feel like he had server settings to use Yahoo for Verizon instead of aol.. But he swears he didn't.. Any ideas would be great help.. Thank u in advance