Hello Cr,
Thank you for reaching out to the Microsoft Community! This is incredibly frustrating, and I truly understand how upsetting it must be to lose access to your files after carefully preparing to leave your institution and unlink OneDrive. Even though you set all files to be available offline and saw the green checkmarks, OneDrive’s sync behavior can be misleading. Files marked as “available offline” are still tied to the cloud, and when you unlink or disable syncing, those files may be removed from your local system if they weren’t fully downloaded or cached properly.
The issue with the ZIP file showing as empty is also common when OneDrive’s download process fails silently or when the ZIP is corrupted due to sync interruptions. Unfortunately, if the files were never fully downloaded or were deleted during the unlinking process, they may not be recoverable from your PC or even the Recycle Bin.
You can check OneDrive Online Go to OneDrive.com and sign in with your account. Look in the Recycle Bin and Personal Vault (if used) to see if any files are recoverable. you can also do fully remove OneDrive, Uninstall OneDrive via Settings → Apps → Installed Apps then delete leftover folders
Example
C:\Users[YourUsername]\OneDrive
C:\Program Files\Microsoft OneDrive
Feel free to reply for better understanding.
Warm regards,
JayMark