Only 7 - the first seven of the alphabet : A, B, C, D, E, F & G.
There are more than seven notes available in music however, as there are sharp and flat versions of each note, all of which have an equivalent sharp/flat.
all the letters are not used but the answer is SUM
Talked, wrote notes and letters. Many of the letters still exist.
Trivandrum
It is an input device for a computer with letters, numbers and symbols on it. It can also be used in playing music.
not to many(if any) movies, but many UK tv series have used their music
21. The letters Q, U, X, Y, and Z are not used.
Many of the terms used in formal Music Theory are Italian.
There are 24.
There are many different systems of using numbers to represent letters. Binary is commonly used.
29 (including Z which is only used in foreign words.)
29 (31 if you include the letters Q and X, which are only used in loanwords).
26, including letters used only in loan words from English and Spanish.