My music started to play in alphabetical order instead of customised.

On iTunes my downloaded music started to play in alphabetical order instead of a customised. However, each song remains just as I arranged so in my playlist, but when it switches to a next one it jumps straight on the one that begins with the same letter.

On my laptop that I synchronised my iPhone with, the playlist is completely fine. I didn't switch any settings as long as I remember. Please help me fix it.

(Picture One - Alphabetical order)

(Picture 2 - My normal order)