Sometimes when you clean the oven you accidently set the auto timer - which people very seldom use...
Switch off the electrical supply to the oven and turn it back on again - the timer should flash - depress and hold in buttons 2 & 3 from the left and use the ± buttons to set the time (any old time will do) let go the two buttons.
If the oven does not work now you may well have a fault that will cost money to repair...
Good luck...
Peccavi, May 2009