Because SQL Server 2005 is "End of Life" (EOL), you will not find a direct "Buy" or "Download" button on the current Microsoft Data Platform site. Instead, users typically access the ISO through the following channels:
Downloading requires navigating legacy software archives, as Microsoft officially ended extended support for this version on April 12, 2016 . While it is no longer available via standard modern download pages, it remains a critical requirement for maintaining legacy business systems that cannot yet be migrated. Where to Download the 64-bit ISO download sql server 2005 standard edition 64-bit iso
Because Microsoft no longer issues security patches for this version, any server running it is highly vulnerable to modern exploits. It should only be used in isolated, non-internet-facing environments. Microsoft SQL Server 2005 - Microsoft Lifecycle Because SQL Server 2005 is "End of Life"