Hi ,
I'm Dyari. Thanks for reaching out. I will be happy to assist you in this regard.
Are you using the Outlook App? Please access it from the web to see if the files are available:
https://outlook.live.com/mail/
If the files are available, click the OneDrive icon on the Taskbar > Check if it says Paused, Signing in, Processing changes, or shows an error.
If you have more than one account, the folders may be under the other OneDrive location.
You can also click Start and open Run > Paste this, and hit enter:
%localappdata%\Microsoft\OneDrive\onedrive.exe /reset
Then wait 2 minutes. If OneDrive does not reopen, open it manually from the Start menu to see if the issue is fixed.