Sponge is right, you need to supply a bit more information.
If the beer was an AG brew the most likely cause is starch or protein haze, if as you say it's "white" then starch is the most likely, mostly from fine flour getting into the kettle, sparge/mash out too hot and not effectively separating your hot break.
For both AG and kit/extract, yeast is a good possibility, tho if you cold crashed for 2 days there shouldn't be enough yeast in the beer to make it white.
If you want a better answer, give your method and a bit of info on your process, ingredients, OG and FG, type of yeast, packaging method bottles or kegs...
Mark
Edit: - A photo could be very helpful
m