I have few .mp3 files in C:\MP3 folder
a.mp3
b.mp3
c.mp3
..
..
..
z.mp3

These files are of duration 10 seconds

In an excel file, I want a text box that should allow two characters.

The moment I open the excel file, it should take the cursor in that
textbox automatically.

If I type "A" in the textbox, it should play a.mp3 file without opening
the mp3 player. (I am using musicmatch/windows media player mp3 player)

If I type "B" as the second character in the textbox, it should erase
"A" which was entered earlier, show the character "B" in the text box
and play b.mp3 file.

If b.mp3 is playing and before the song is over (before 10 seconds) if
I enter C as the second character in the textbox, it should stop b.mp3
song and start plaing c.mp3

If I type any other character or if I press any other key besides A-Z,
it should stop the current song and should not play anything, it should
just erase value in the text box and place the cursor there and wait
for an A-Z input.