If you originally purchased AutoCAD 2011 on a DVD, that remains the most reliable way to reinstall the "full" 64-bit version. Critical Warning: The Activation "End of Life" July 1, 2022
However, here’s what you can do instead: autodesk autocad 2011 64bit download full
After installation, you'll need to activate and register your copy of Autodesk AutoCAD 2011: If you originally purchased AutoCAD 2011 on a
Official downloads for Autodesk AutoCAD 2011 64-bit are no longer available directly through the standard Autodesk Account portal If you manage to locate your original installation
: AutoCAD 2011 reached the end of its product lifecycle years ago. Autodesk typically only supports the current version and up to three versions back.
If you manage to locate your original installation media or a legal backup, note the following requirements: 2011 autocad lt from 32 bit to 64 bit - Autodesk Forums
These are critical for fixing bugs and improving stability.