Walter recently logged into Windows 10 and his profile has gone blank. What happened? Leo says that a recent Windows 2004 update has a bug that caused the profile to disappear. The good news is, that your data is still there on the hard drive, the so-called "new profile" just can't see it. KB4549951 is the update. One solution people have reported is to reboot your machine six-eight times. That brings back your data. The profile may also be there in settings but renamed with .000 or .bak. Browse around for a file with your login name with those extensions. Rename it. That could help. Once you get it all back, it's a good time to make a backup and an image of your drive so that you can restore it.