I did not know that there is no backup/restore option for users who store their files in their One Drive for Business file space. If you *delete* a file, you can recover it for a period of time and if you have versioning turned on, you can go back to a previous version.
But if, as one user found out today, you manage to run a Crypto-virus application and have your One Drive for Business folder synchronised to your computer, you can kiss all your files goodbye. The encrypted files, apparently, are considered to be new files, not new versions, and because the existing files were changed on the user's computer, the old files don't appear to go through the recycle bin.
Now, if this data had been sittingon an in-house server, we'd have shadow copies, online backup and offline backup from which to choose ... but we have none of these today so...