First I did this: 1. In the Control Panel, select System. 2. Select System Protection. 3. In the Protection Settings section, select the D drive. 4. Click on the Configure button. 5. Enable Only restore previous version of files. 6. Set Max Usage to 50%. 7. Click on the OK button. 8. Click on the OK button. 9. Close the System dialog. after several weeks, when I right click on a file that has been modified several times, the Previous Versions tab is empty. Somehow my Restore point got deleted. After creating a Restore Point, it is working correctly.