1) Power outage is major cause of timer failure. Power surge occurs when power is restored, and electronics are susceptible to surge. This includes water softerer, treadmill, electronic water heater, timers, etc.
Timers should be unplugged when power goes off.
Of all timers on market today, only one instruction manual says to unplug timer with power loss. However many people write fixya saying their timer, and electronic water heater control etc stopped functioning after power loss. Probably other products have same problem, but I work with timers and water heaters and see only that slice of the world.
2) Question posted under Woods 59377.
Several timers look identical or similar.
59377 timer has non-replaceable rechargeable battery, some similar timers have AA battery.
If timer has battery, change battery.
Then reset timer to restore functionality. Press reset button for a few seconds with paper clip.
3) If timer function does not restore after reset, then timer is bad.
Buy similar timer at Lowes or Target, and return defective timer in new package.
4) If function is restored, then re-program timer
Open following link for timer instructions showing how to reset timer and re-program timer:http://waterheatertimer.org/How-to-program-Utilitec-0155671.html