I have few .mp3 files in C:\MP3 folder. All .mp3 files are of duration
10 seconds

a.mp3
b.mp3
c.mp3
..
..
..
..
z.mp3

I want a textbox that should allow only one character.

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

If I type "A" in the textbox, it should play "a.mp3" file after 10
seconds (when the song is over), it should stop the song and take the
cursor back to the textbox for another input.

If I type anything besides A to Z keys, it should erase all characters
in the textbox, take the cursor in the textbox and do not play
anything.

I use Musicmatch and Windows Media Player to play .mp3 songs.