Why didn't you graduate from junior high school? I know a second-class architect who didn't graduate from junior high school and took the exam himself, so don't lose heart and don't worry. You can start with some high school books or enroll in some adult university classes.
Which subject do you want to study? Liberal arts or science? What is your major? In fact, there is no need to read those rigid and dogmatic textbooks, because everything taught in college is useless and many of them are ridiculous. You can read some books you like and go to the library to find some related materials. If you don't understand, ask the librarian or the classmates around you, and everyone will enthusiastically help those who want to learn, regardless of age.
Come on! Wish you success!