Hi @jessicasan10475
Here's the [document|40786|service manual] for the model that may help.
Go to p.23 of 60 (pdf) to view the procedure to run the diagnostic tests.
Perhaps start by running all the tests applicable to the door switches and the lights.
If you find the problem and it is a faulty part that needs replacing, here's the [https://www.searspartsdirect.com/model/p917nszmni-001198/whirlpool-wrx988sibm03-bottom-mount-refrigerator-parts|parts list] that is useful.
Locate the wanted part in the list and note the ''manufacturer's part number'' that is shown with it.
Search online for the part number only, to find suppliers that suit you best.