The coils you see on the back of your dehumidifier are the evaporator. When the unit runs, the coils get very cold. As the fan draws the room air over the coils, the humidity in the air condenses out of the air onto the cold coils. But, if the temperature of the air the fan draws over the coils is too cool, the humidity that condenses out of the air freezes on the coils.
To remedy this problem, you can try any of these:
Warm up the room the dehumidifier is in.
Put the dehumidifier on a sturdy table (the room air is coolest near the ground).
Your dehumidifier has a circulating fan that draws the room air over the coils. If there's no air movement out the front or back of the unit, the fan motor may be burned out or stuck, or the fan blade may be broken. If so, you need to replace the fan motor or the fan blade.
The tank may be full. Your dehumidifier has a safety device that turns off the dehumidifier when the water tank is full. Usually the tank itself either presses against a switch or there's a device connected to the tank that triggers a switch when the tank is in place and full.
If you've emptied the tank and the unit doesn't run, inspect the place where the tank rests to see if there's a switch or mechanism that's not being activated. You may be able to turn it on with a simple flick of your finger.
When the container fills quickly, your dehumidifier is doing its job. If the container fills quickly for many days in a row, you may want to locate the source of the humidity (for example, is there an unsealed crawl space?) and see if you can correct the problem at the source.
If your dehumidifier doesn't seem to run often but the humidity in the room is high, try adjusting the humidistat control on the dehumidifier to a dryer setting. If the dehumidifier seems to run constantly, but there's little or no water in the container, there may be a problem in the refrigeration system. Try cleaning the unit. If that doesn't work, you can't repair the refrigeration system yourself, you need a qualified appliance repair technician to do that.
