The corrected version is "Even a stopped clock is right twice a day."
For those using a 24-hour digital clock, this may be further updated to "Even a stopped clock is right once a day."
Or, if you must keep the broken: "Even a broken clock may be occasionally right on a regular or irregular basis, depending upon the nature of the malfunction."
For those of you who have digital clocks and the LED-display is busted, I don't know what to tell you. Try Radio Shack and see if they have a replacement display. If you are like me, you will spend as much on a replacement display as you would pay for a new clock, and then you would break something else trying to replace it, and you would get mad and smash everything and then you would go to Meijer and buy a new clock. (That didn't really happen, but I could see it happening.)