Most probably it needs cleaning. You can buy an inexpensive vinegar with a cleaning strength at Walmart. What you need to do if its not dripping water is to:
1. With tap water inside reservoir, try to run it on 12 ounces. If it didn't work, unplug it then plug it back in and set it on 12 ounces again, until it drips fully.
2. Continue to run it until water in reservoir is consumed.
3. Fill up the reservoir with the vinegar and continue to run it 12ounces at a time.
4. When the vinegar is almost out, run it again at 12 ounces this time when it starts to drip, turn it off.
5. Wait 4-5 hours then turn it on and start cycle. If its dirty you may need to fill up the reservoir with vinegar and do process again.
That solve the problem with my Keurig.
Hope this helps.
Jon 02/26/13