Even though it’s pre-installed, it might be disabled (usually because you installed another antivirus). Here’s how to check:

If you prefer to use direct download links, here are the links to download Windows Defender for Windows 10 64-bit:

To download Windows Defender for Windows 10 64-bit, follow these steps:

However, if you feel the software is missing or you need the latest security definitions, follow this guide to verify, repair, or update your protection. 1. How to Access and Enable Windows Defender