If it's 6th Generation It's stil under the Apple One Year Warranty. You can always set it on the counter and lightly tap the corner where the volume buttons are. If that doesn't work call Apple and have them set it up for replacement.
There is a simpler way to go about it. Try cleaning it with alcohol and cotton swab. The buttons accumulate dust and sweat around it and get jammed. I had similar problem and tried it and the buttons work !