Lost all calendar and contacts in outlook

Calendar and contacts data in Outlook is stored in the mailbox (for online accounts like Gmail) or in local Outlook data files (.pst or sometimes .ost). When sync is “fixed” or an account is re-added, Outlook may show an empty calendar/contacts if:

• The account was added using IMAP/POP instead of an Exchange/Google-type connection (IMAP/POP only sync email, not calendar/contacts).
• Outlook is now connected to a different data file/profile than the one that previously contained the calendar and contacts.

To recover what is possible:

1. Confirm the account type
   • In Outlook, open the account settings and check whether the Gmail account is configured as IMAP/POP or as an Exchange/Google-type account.
   • If it is IMAP/POP, only email will sync; calendar and contacts would have been stored either:
     • In a separate local .pst file (for “On this computer only” folders), or
     • In Google (if they were originally Google Calendar/Contacts).
2. Look for old Outlook data files (.pst)
   • Use File Explorer and check typical locations for old Outlook data:
     • C:\Users<YourUsername>\Documents\Outlook Files\
     • C:\Users<YourUsername>\AppData\Local\Microsoft\Outlook\
   • Look for .pst files. These may contain the missing calendar and contacts.
3. Attach the PST in Outlook
   • In Outlook (classic desktop):
     • Go to File > Open & Export > Open Outlook Data File.
     • Browse to the .pst file found in step 2 and open it.
   • A new folder tree will appear in Outlook. Check the Calendar and Contacts folders under that data file.
   • If the old items are there, they can be used directly or imported into the current mailbox.
4. (Optional) Import into the current profile
   • If the old calendar/contacts are in a PST and should be merged into the current account:
     • File > Open & Export > Import/Export > Import from another program or file > Outlook Data File (.pst) and follow the wizard.
5. If data was only in Gmail
   • If calendar and contacts were originally in Google (Google Calendar/Contacts), sign in to the Google web interface and verify whether they still exist there.
   • If they do, ensure Outlook is connected using the supported Google/Exchange-type connection so that calendar and contacts can sync, not IMAP/POP.

If no PST with the old data exists and the items are also missing from Google’s web interface, the calendar and contacts cannot be recovered from Outlook alone.

References:

• Can't sync calendar and contacts with my phone or tablet
• Known issues syncing Google accounts to the Microsoft Cloud
• How do I recover my old email messages, my contacts and everything else I had in Outlook? - Microsoft Q&A