Hi.
Without the full model number (as written in service tag) I cannot locate the manual.
Please check if oven is in manual mode and try the following. Try also pressing down main knob.
If you have a timer with a dial on it, please ensure that the function
indicator has a hand in it for manual control and make sure the time of
day hands are locked with the time to start hand.
I think this model is fully digital.
If your control timer is digital then the control indicator should be set to manual as shown.

If that does not fix the problem, then please provide full model number or
enter model number here.