first thing I would suggest is a hard reset. Unplug the unit for a
minute or so. Then plug it back in, set the clock and try again.
If that doesn't work, leave it unplugged for maybe an hour. Then let us know if the hard reset does not fix it.
You may instead have a failed keypad.
If you (or someone you know) might want to replace it yourself, I have uploaded a handy guide with pictures
showing you what's typically involved.
If you would like to have us do this for you, we do that for $39.95 plus part costs, which depends on the exact model, one of these:
NNS688BA NNS688BAS NNS688LA NNS688LAS NNS688WA NNS688WAS
Please feel free to contact me directly if you need more help.We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.