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.
At our site, we now have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.
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.
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.
You can probably find exploded views and order parts by entering your model number here at the
Sears parts site. The best place to order Sharp parts is
Tritronics.
You can usually find helpful exploded view diagrams and order parts for most non-Sharp models by entering your full model number
here.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.