A Microsoft file hosting and synchronization service.
Hello, thank you for reaching out to Microsoft Q&A.
Did you receive any notification from Microsoft a few months ago, or recently, saying that your storage is full and your files will be deleted?
(Example email screenshot for your reference)
If you exceed your OneDrive storage limit, your account will be put into a frozen state and you will no longer be able to sync any files to OneDrive or send and receive emails. Microsoft will notify you that your storage is full and that your files will be deleted. After six months, your files will be permanently deleted and cannot be recovered.
To check if you have enough storage, go to https://outlook.live.com/mail/0/options/accounts-category/storage, expand the Microsoft Storage and email storage section, and see if you have enough space there.
If someone hacked your account, it is possible that the hacker might have deleted all of your files from the OneDrive. Please check your OneDrive recycle bin folder and see if you can recover the files from that folder.
Also see,
How to help keep your Microsoft account secure
Let me know if you still need more help.