Since no new security patches exist:

If you are using a branded machine (e.g., Dell or HP), you may be able to use tools like the Dell OS Recovery Tool

If you are looking for a solutions, this guide covers everything you need to know—from safely sourcing the installation files to activating your system legally.

This method allows you to use your old product key and ISO without risking your main operating system.

For users who own hardware but lost the installation media, many users turn to trusted repositories like the Internet Archive (Archive.org). The community has preserved official, untouched ISOs. When using this method, you must verify the ISO's . This ensures the file is an exact copy of the original Microsoft release and hasn't been tampered with.

These were bought in a box and can be moved from one PC to another.