Q: All the content is gone from my Computer.  The only way I can see or access my music is to plug in my iPod.

All of my music content is gone.  When I open iTunes, I get the generic home page & no library.  I have a third( I think) generation iPod Nano, and Iphone 3GS (which I use as an iPod Touch) and an iPhone 4S (soon to be replaced).  The content on my phone(s) is not the same as on my iPod.  I would like to update phone libraries but can't because my base library (which used to live in iTunes) is no longer there.  I recently updated my PC operating software to Windows 10.