If the cooker timer has a row of buttons underneath and the numbers are flashing do this...
Depress and hold in buttons 2 & 3 from the left and use the ± buttons to set the time (any time will do) and then release all buttons. After a few seconds the clock will show the time you set and the oven should work.
If the clock numbers are not flashing turn the power to the cooker off and back on again - the colock will flash - asking you to set the time...
Peccavi
May 2009