1. Make sure the outlet where the controller is plugged in is working and you're not just running off of the back up battery.
2. Go out to the valves and turn one on manualy. Make sure there's water at the valves. Maybe someone turned off a valve.
3. If you haven't found the problem via number 1 and number 2 and don't have a master valve or pump then it's a wiring issue. Probably the common wire is broken somewhere or came off at the valves.