I get asked a lot by students exactly how I work songs out for myself. That is, by not using any sort of tab, chord chart or YouTube video—nothing but my own hands and ears.
Often a student is really keen to learn this skill but they cannot believe it is something they can acquire. They see working songs out by ear as a mystical skill that only wizards such as Gandalf and Merlin could acquire (just imagine those two rocking the guitar!)