Freezer not working, makes buzzing noise

The last 3 days the buzzing noise comes from the bottom of the refrigerator, the freezer is on top. The noise goes on about 10 to 15 seconds, stops a few minutes, then buzzes again. During this time the freezer has stopped working almost entirely, everything has thawed out. The refrigerator is also not cooling enough now, it’s 54 degrees. This is a Kenmore, 5 years old. I called Sears for repair last Thursday, but they can’t come until next Wednesday. Is it safe to leave the refrigerator running or should I unplug it? Also any ideas what’s wrong with it?