Door

What usually breaks is the door open lever.

On a counter top model, the outer cover will need to be removed to diagnose and repair this. On an over-the-range model, only the control panel needs to be removed.

Please unplug the oven first.

If you or someone you know wants to look into this, we have critical safety, disassembly, and troubleshooting info at our site, and our link is at our listing here on FixYa: http://tinyurl.com/yzjozk

Once it is apart, you'll be able to see how the door open button would press against the door open lever, which would then lift up against the door latch heads (hook-like projections on the door) and the door should open.

If you reply back to this with your brand and model number, we can steer you toward a part source, and possibly toward exploded view diagrams, etc.

We're happy to help and we appreciate your thoughtful rating of our answer.