What are the only 2 musical notes with no flats?

== == All notes may be raised (sharped) or lowered (flatted) a half step. What you -- or your teacher -- are alluding to are the notes F and C. Lowering an F one half step produces an E natural. Lowering a C one half step produces a B natural. It is perfectly acceptable, however, to write F-flat and C-flat, although it is uncommon. Those notations are occasionally seen in key signatures where the E or the B is already flatted but the natural, unaltered note is called for in the same measure as the altered notes. Writing Cb for B and Fb for Emay reduce clutter on the staff. But keep in mind that on a piano keyboard no black key exists between B and C, or E and F.