Your post was branched and moved to a better forum, LrC.
You are Out Of Luck unless you have a Saved Copy of the origiina Lr 3.6 install file.
Back then, some 9-10 years ago, all updates for Lr were the complete install files for the complete program. Not just a bunch of file that replaced the previous point release of whatever major Lr version.
So if you have your old computer look on the drive for a Lr 3.6 install file.
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