Epoxy resin will sometimes turn cloudy and possibly form into crystals.  This is usually t' result o' exposure t' cold temperatures.

Don't throw it away! 

T' solution is t' warm t' epoxy resin t' dissolve t' crystals. Place t' epoxy bottle in a pan and fill t' pan with water heated t' around 100 degrees F.  T' crystals will dissolve should nay return even after t' resin is colled back t' room temperature.