All of my vocals I had typed out with the chords on top of the lyrics. Can't remember all the lyrics as I started doing vocals late in life.

I always studied the chords to everything I played for the most part and the ones I didn't know I'd have the pianist or guitar play whisper them in my ear as we played the gig and I could get by with most tunes playing melodies and improvising with the Sax.

If you aren't able to listen to a tune and hum it, forget about playing by ear. If you can't do this then you are tone deaf.
You must have an ear.