Diagnosis
Both LED modules have failed or the wiring harness connector to them is loose. They are not user-replaceable bulbs.
How to Fix It
Check the connector. Unplug the microwave and lower it. Locate the white rectangular connector going to the light board on the underside. Reseat it.
If That Didn't Work
The entire LED light assembly (part # DA97-14133A) must be replaced. It's a single unit containing both LED strips.
Heads Up
There is no direct user serviceable light bulb. Attempting to pry the lens cover off will break it.