Please run the below powershell command as an admin:
1.If you know the URL of the OneDrive, run the following command:
Get-SPODeletedSite -Identity <URL>
2.If you don't know the URL of the deleted OneDrive, run the following command:
Get-SPODeletedSite -IncludeOnlyPersonalSite | FT url
If the OneDrive appears in the results, it can be restored.
You can try Search the audit log in the compliance center, where you can check whether users download files and some other activities.
Search the audit log in the compliance center
A similar post for your reference:
sharepoint audit logs
Overwriting a file does not affect item permissions. Follow below steps:
Create SharePoint group (SPGroup) from 'People/Groups' under site settings. Make sure not to assign access level yet
Go to documents library and open item permissions of the documents that you want 'to restrict to' or 'provide access to' and break the inheritance
Grant access to the ...