Robert has a Dell Inspiron running Windows 10, but his restore point keeps getting deleted. Leo says that Microsoft deprecated System Restore recently, and Leo says it has never really worked when he needed it the most. He can still use it, but he will need to re-enable it. Windows Key + Restore. Here's a link from the chatroom about this issue, but it's a few years old.
There's also this article from The Verge. But the first thing that Malware will do is remove a restore point. So it's possible there's malware hiding in the background. Also, don't use a third-party antivirus. They can often do unpredictable things like this. Windows Defender is built-in and will work just as well.