During a process of syncing emails and PSTs to a client's office 365.  He is saying as I was doing this (from another computer connected into his account) tasks that he had on his computer are gone and it is vital that he gets them back.  He doesn't know specifically when they disappeared, but he knows it was within the past two weeks.  

I am currently restoring deleted items to a temporary folder, but I need other ideas.

Hi JFarling,

According to your description, I know that the emails gone from his computer after exporting to .pst files.

Please correct me if there is anything misunderstanding.

Based on my knowledge, exporting to .pst files cannot remove the emails from the resource. The mailbox move request can remove the emails from the resource.

I want to double confirm the account type. Is it an Exchange account, or IMAP/POP account? If it is an Exchange account, how do you configure the account on Outlook, MAPI, IMAP or POP?

I suggest check the account with OWA to verify whether the emails exist in his mailbox.

If everything works well, please try to re-create profile on Outlook.

Thanks