No wonder I got nowhere trying to learn to play
It's never too late to start it back up.
I highly recommend 'Theory Notebook Complete' by John Brimhall for those not studying Music Theory as part of a full curriculum and even for those who are studying music theory in school.
https://www.amazon.com/Theory-Notebook-Complete-John-Brimhall/dp/158560755X
The Berklee Music Theory books are also good.
https://www.amazon.com/Berklee-Music-Theory-Book-1/dp/0876391102/ref=sr_1_1?crid=COSWOCCYGFT5&keywords=berklee+music+theory&qid=1707632266&s=books&sprefix=berklee+theory%2Cstripbooks%2C88&sr=1-1