Organizing and accessing contact information in Outlook.com
I understand how concerning it can be when your contact lists suddenly disappear.
Before we can determine the cause, could you please confirm:
- Are the individual contacts still present, and only the contact lists are missing?
- Did the lists disappear recently, or have they been missing for a longer period?
- Can you see the lists when you sign in at People/Contacts in Outlook.com?
In the meantime, please check the following:
- Sign in to Outlook.com and open "People".
- In the left pane, select "Deleted" and see whether the missing contacts or contact lists are available for recovery.
- If you find them, select the items and choose "Restore".
Microsoft's guide for recovering deleted contacts can be found here: Restore or recover a deleted contact in Outlook
If the contacts are still present but only the lists are missing, please let me know the answers to the questions above so we can narrow down the issue further and provide the next steps.