I use a software that shows all the notes for any song in a virtual keyboard, using MIDIs.
MIDI it’s like a digital sheet. In fact MIDI it’s better because it’s easier to find songs in internet and you can also hear the notes simultaneously as you viewed.
Do this:
1- Search the WEB for the song you like to learn in http://www.midisite.co.uk/ or http://www.musicrobot.com/
2- Open the MIDI file in this software: “Sweet Sixteen MIDI Sequencer 3.3.2” that you can download free in http://www.download3000.com/download_32086.html or http://www.download32.com/sweet-sixteen-midi-sequencer-i3153.html
3- After that, go to the “Grid” section and you’ll see all the notes you need to play for that song displayed in a keyboard inside of the software. All you have to do its repeat the notes displayed.
I learn to play piano like this on my own. You should try it.
Note: Sweet Sixteen MIDI Sequencer is free in trial version but it works well. If you want you can also buy it.
I made a video showing how to learn to read music for piano without sheet using MIDI; watch it: http://www.youtube.com/watch?v=-LYSVjFU3Jw
Tell me how it goes.