In most combination units, cold air is pushed from the freezer to the refrigerator, which means a malfunctioning freezer usually results in a warm refrigerator. Occasionally, however, a problem will appear that affects only the freezer. This usually indicates a simple problem with a simple fix.
The temperature control for the freezer may have been turned off, accidentally bumped or set to the wrong temperature, causing the freezer to be too warm. Check that the freezer is turned on and it is set to the desired temperature. Adding a large amount of food, especially warm food, all at one time can cause the temperature in the freezer to rise, and it may take some time to cool. If you just added a large amount of food, give the freezer several hours to a full day to freeze the food. The seal around the edge of the freezer may be leaking cold air, causing the freezer to be too warm to keep food frozen. With the door open, place a dollar bill along the seal then close the door. If the bill falls out, the seal needs to be replaced.