Homemade coconut milk separates into different layers after a day in the fridge I made some coconut milk. After a day in the fridge there was two layers of liquid in the jar, coconut water and solid coconut which I found out afterwards that it is called coconut butter! When I stir them together to  have my coconut milk back, it didn't work. Is there a way to prevent this? If not, is there a way to have coconut milk again?
All coconut milk separates out. When you buy it tinned, there is often a plug of coconut cream above a pocket of coconut milk. But it certainly should recombine. It may well have been too cold when you tried to stir it together - let it come to room temperature at least.  If you warmed it up on the stove you'd find the two would melt together without any stirring necessary.