If a file has been changed and you wish to restore a file to a previous version, follow the steps below. These steps are similar for OneDrive also.
1. Click the ellipsis (...) next to a file.
2. Select Version history from the pop-up menu.
3. Click the drop-down menu next to the version you wish to restore and select Restore.
Note: If this document library is using the Check-In/Check-Out feature, you need to Check-Out the file first.