Can't see or edit contact lists suddenly

Hi igo23, if the list still appears while composing but not in People, it may still exist but the People page is not showing it correctly. Try Outlook on the web in an InPrivate window, then open People and look specifically under contact lists, not normal contacts. If possible, export your contacts before changing anything. If the lists remain usable in compose but invisible for editing, that is likely a Microsoft-side UI/account issue rather than something you deleted.