If all the numbers on your microwave oven are lit up, it is likely that the microwave is in "demo mode" or "display mode." Demo mode is a feature found in many microwave ovens that allows the display and controls to be demonstrated in stores without actually turning on the microwave's cooking functions. In this mode, the microwave will still function as a display unit, but it won't heat or cook any food.
To exit demo mode and return the microwave to normal operation, you'll need to consult the microwave's user manual, as the process may vary depending on the brand and model. Generally, you can exit demo mode by pressing and holding a specific combination of buttons on the microwave's control panel for a few seconds. The specific steps should be outlined in the user manual.
If you don't have the manual on hand, you can try searching for the model number of your microwave online and look for the user manual on the manufacturer's website. If you're still unable to exit demo mode or if the microwave continues to behave unexpectedly, contacting the manufacturer's customer support for assistance would be the next step.