System Restore Points disappear or not showing up on reboot
The following will show you the direction to work in: This post offers more suggestions on what you can do if System Restore Points deleted or go missing.
It has been suggested that the problem could have been caused by resizing disk partitions with a tool that is not yet certified for Windows operation. If you need more suggestions, then this post on Troubleshooting System Restore in Windows is sure to help you.