This is probably a really stoopid question but.....I'm trying to learn to play a virtual keyboard online(Virtual Piano) but its really hard to use the black keys since you need to press Shift+(another key). I thought I read somewhere that each black key has an equivalent sound in some white key or that all western music is in the diatonic scale which doesnt need black keys so I'm wondering if I can learn to play existing music without using the black keys?
You can play any diatonic or modal melodies on white keys only, but anything beyond extremely basic harmonies will require the use of more than seven pitch classes (ABDCEFG).
Of course, a virtual piano played on a computer keyboard is extremely limited to begin with, so perhaps playing melodies is all you're interested in.
To play a diatonic or modal melody on white keys only, you will need to identify the key signature of that melody, and then transpose the notes up or down a number of half steps until they all lie on white keys. If the melody has any chromaticism, or deviation from the key signature using accidentals, this may not be possible.
If the key signature has one flat, for example, you would transpose down five half steps. Two flats and you would transpose up two half steps. Three flats, down three half steps, four flats, up four half steps. See if you can catch the pattern. For sharps, reverse the direction of transposition.