If the water feed line was ran inside or up against the outside wall it could freeze
I don't see too many frozen any more or at least not as many as we did years ago. Power off first, crack open the water fill line at the fill valve entrance ( under the d/w and behind the access panals ) to see/confirm if you do or don't have water flow to the d/w. If the house feed line is frozen you -may- be able to heat up the line with a heat gun....depending on how accesable the water pipe(s) are, if they are covered in a wall you may be waiting until a warm spell or spring before using the d/w again
If the water line is not frozen, the d/w's fill valve or float may be at fault for the no fill problem.
LINK> My d/w won't fill helps