I just updated my itunes to 12.2.1.))16 and it does not find my previous library of music. How do I connect to the old music library?

I logged into iTunes this morning and was requested to upgrade to the latest version, (12.2.1.16). My PC is running Windows 7. After install and reboot, I was asked to log back into iTunes. After logging back in, iTunes does not link to the existing music library. I can find the songs previously stored by searching the C: drive of the computer. I was able to import a CD to the u"new library" but was unable to move any of that music to my iPhone. Any suggestions to link to my previous library? Wish I wouldn't have upgraded!