Select the Recycle bin. (In the taskbar, click the blue OneDrive logo and then click recycle bin).
If you want all of your files back, select Restore all items.
Or, select only the files you want and click Restore.
The file is returned to its original location.
Open OneDrive settings (select the OneDrive cloud icon in your notification area, and then select the OneDrive Help and Settings icon then Settings.)
Go to the Sync and back up tab.
Select Manage Back up.
To start backing up a folder, toggle any folder that says Not backed up, and then select Save changes.