Q: Connect/restore iTunes Library located on a secondary drive to a new iTunes app to be installed on a new system drive (C, Windows 7)?

Update -

Perhaps I should have waited a bit longer, studied a bit harder, before posting my question.  I did eventually solve this problem, mostly by reading a lot of not very helpful and a few very helpful articles/posts.  Among the most helpful were an oldish article (Nov. 30, 2011) by Jesse Hollington in iLounge (http://www.ilounge.com/index.php/articles/comments/moving-your-itunes-library-to -a-new-hard-drive/) and a more recent Apple Support Community standalone post (last modified July 4, 2015) by turingtest2 (Make a split library portable), which also provides links to other support documents and discussions of similar issues.  Of course other articles/posts also helped along the way, but (predictably) none set forth a step by step procedure that was exactly applicable to my particular situation.

After reading turingtest2's article, I realized that I had only partially split my iTunes and wanted to fully split it (to make it more portable), so I followed his instructions and moved all the folders in the iTunes folder (except the iTunes Media folder) that I had saved from my previous, too dysfunctional C drive, to the iTunes folder on my D drive (after having saved elsewhere [in case I might need them] all but the iTunes Media folder from the D drive, which I left because it holds all my music).   

Next I installed the latest version of iTunes (12.2.2.25x64) on my 'new' (clean install of Windows 7 Enterprise) C drive and set iTunes to find its way to my iTunes Media folder on my D drive through iTune's Edit->Preferences-> Advanced Preferences function.  Because I don't want iTunes to mess with my Music folder (which contains many more artists and albums than I've put into iTunes), I made sure that both 'Keep iTunes Media folder organized' and 'Copy files to iTunes Media folder when adding to library' were unchecked.  For similar reasons I had always stayed away from the iTunes 'Organize Library' function and its two checkbox offers to Consolidate and/or Reorganize Media folder files for you (of course these functions might be relevant for users with different needs).  Then I closed iTunes.

Finally, I crossed my superstitious fingers and opened iTunes while depressing the Shift key, clicked 'Choose Library' (rather than 'Create Library'), navigated to my D drive's 'iTunes' folder and, within that folder, clicked on the 'iTunes Library' folder (which contained several files gathered, it seems, under this name by the new iTunes, including their [apparently] recreated but [apparently] identical version of the crucial iTunes Library.itl data file whose most recent version I had earlier copied into the iTunes folder along with other files/folders recommended by turingtest2).  Within a few seconds my 'new' iTunes opened and, to my relief, it contained everything and did everything that my previous iTunes contained and did...along with one pleasant surprise: viz., I discovered that music CD's ripped 4 to 10 times faster (previously up to ~9x, now as fast as ~47x).

Thanks turingtest2 and Jesse Hollington (and a few others) for helping me get my iTunes back...and make it more portable!

Thanks, alex-hl, for your identification of an important part of the process which got my iTunes up and running.  As my Update post shows (which I must have been writing while you were replying), I didn't quite understand the complexities of my situation when I first posted.  Hopefully others will benefit from your guidance.  I appreciate your expertise and generous spirit!

Thanks for the good will, turingtest2.  Happily, I discovered that you had already answered most of my questions (including questions that I wasn't aware I should have asked).  Worldwide, users of Apple, Microsoft, and other products have been very fortunate that you have been so willing and able to help them.

THANK YOU!