If you are actually using an older OS like Windows XP x64 Edition or Windows Server 2003, you can still find the original redistributable.
Always download from official Microsoft sources to avoid malware. Here are the two primary URLs that still serve the : net framework 20 offline installer 64bit
Yes, Windows XP had a 64-bit edition (based on Windows Server 2003 kernel). The .NET Framework 2.0 64-bit installer is fully compatible. Simply download and run the same NetFx20SP2_x64.exe file. Note that Windows XP x64 requires SP2 of the OS itself. If you are actually using an older OS
Offline installers (also called redistributable packages) contain all the files required for installation without an active internet connection. This is ideal for: Microsoft .NET Framework 2.0 Service Pack 2 (x64) LangPack net framework 20 offline installer 64bit