Someone appeared to control my PC remotely. What should I do next?

First, disconnect the PC from the network, including Wi-Fi. From a different trusted device, change the passwords for important accounts used on that PC, especially email, and review their security settings and recent activity.

Back up important documents and photos before doing anything drastic. Avoid relying on programs or installers from the affected machine. If someone really had control of it, a clean Windows installation from USB is the more cautious route. A clean scan doesn't prove the system is clean.

Net use is a valid Windows command, not necessarily a mistyped net user. It can show or manage network connections such as mapped drives. Net user is a separate command for viewing and managing user accounts.

The command alone doesn't tell you what the person intended or whether anything was taken. But a command prompt typing by itself is enough reason to treat the machine as potentially compromised.

If you're not ready to reinstall, you could run a Microsoft Defender Offline scan as another check. Also look through installed programs sorted by installation date and note anything unfamiliar, particularly remote access tools you didn't knowingly install.

Don't assume an unfamiliar entry is malicious without checking it. Legitimate remote management software may not be flagged by a malware scanner, and even a second clean scan can't rule out a compromise.

Spacedesk stopping at the same time is a clue, not proof of how access happened. I'd check where the installer came from and review its connection and security settings before using it again. Something else on the PC could also have provided access.