when you first start inventor and open "projects" ( without opening or starting a new part or assembly) can you see your library listed.
If you don't want to mess around with your current projects start a new one
when you have named it and selected single user project the next step is to choose you library either and existing one or type in a new name and inventor will create one.
Its always a good idea to have your "own" library for custom parts
I was able to narrow down what initiated this problem to begin with.
When I downloaded Inventor I did not choose to download Library (parts Library) to desktop.
This forced Inventor to look for libraries on the website and asking me to sign in to download Data Management.
I am enclosing screenshot of that.
I was unable to sign into that.
So for future users of Inventor: When one first downloads Inventor to their computer choose Download libraries to Desktop.
Autodesk software re-seller was very unwilling to help me with resolving this issue without me paying " through the nose" as much as I was entitled to their support.
Autodesk software support experts were more then glad to help and now I am able to create Custom Parts Library.
The fix you describe works but only after one solves issue with improper initial download of Inventor.