Apparently stripped holes in dryer door hinges
The hinge screws do not engage threads in the sheet metal of the front panel, they are bolts designed to be held in place by nuts, which fell down inside your dryer when you removed the door.
Well, not nuts exactly. The retaining parts are actually small metal plates, one per hinge, with two threaded holes each, that align with the holes in the front panel.
You will have to remove the front panel to install the door. Fortunately this is very easy: remove the two screws near the bottom of the panel, pull the bottom of the panel out, and slide the panel down to disengage it at the top. Disconnect the door switch wires and remove them from the front panel.
Find the retaining plates that have fallen down inside the dryer. It should be obvious how to use these to attach the door to the front panel. A dab of construction adhesive or contact cement might help hold the plates in place during assembly.
Don't forget to re-connect the door switch wires. Close the door before installing the front panel; this job does not require any comic relief.