Who should I ask for recommendation letter after graduation?
Attempt to contact your previous instructors, wherever they have moved to. At least they know you. Professors and academics move around a lot and their recommendation letters are still valid and respectable. If moving around is a barrier to recommendations and support letters, I think academia will cease to function...
Whatever you are doing now (post-graduation) is likely to be relevant and may be helpful. Any jobs or roles that you have held will support your work especially if they are in the research/writing vein.