One thing to do is simply to let your freezer (or whatever compartment the ice-maker is in) thaw out for a while, and then see if you get water flow into the ice-maker later.

You can also manually operate the ice-maker water-fill valve. If you have a Whirlpool (or related) refrigerator, the ice-maker water-fill valve can be operated by putting a jumper-wire between the N and V test points on the ice-maker control module. You can usually access this by removing the ice-bin, and then removing a snap-on cover that sits over the end of the ice-maker. The second you touch these two points together with the jumper wire, you should clearly hear the water-valve operating, and then water should be filling the ice-maker tray. If you don't hear anything, then possibly the water-valve itself is shot. If you hear a sound like the valve is operating, but no water comes into the tray, then it points to a blocked water line (frozen, or possibly some other form of blockage).

You don't want to do this if the ice-maker tray is already full, of course.

You can also try manually forcing an "ice harvest" cycle, by jumpering the H and T test points together. You want to connect them for several seconds, but then remove the jumper as the cycle starts. If nothing happens at all, then the ice-maker is probably bad. If the ice-maker mechanism goes through a cycle, then you can see if the cycle ends with a water-fill. But in any case, if the forced harvest seems to "work", but you weren't getting any automatic harvests, then it might be the thermostat within the ice-maker unit that is bad.

The jumper wire for either of the above tests is just a 6" or so length of 14-gauge wire (insulated), with a half-inch or so of insulation removed at both ends. Bent into a U-shape, you can insert the ends into the appropriate test points, being careful not to be contacting any bare-wire with your hands, fingers, etc. (or pliers, for that matter)