If Windows Defender is missing and is gone or has disappeared in Windows 11/10, here are some suggestions that are sure to help you resolve the issue.

Disable/Uninstall 3rd party security software Check Windows Defender service status Re-register Windows Defender DLL files Run System File Checker.

A Windows Defender bug creates thousands of small files that waste gigabytes of storage space on Windows 10 hard drives.

A Windows Defender bug is reportedly negatively impacting the performance of Intel-based Windows 10 and Windows 11 PCs.