Worked fine for nearly 3 years; recently noticed frost on refrigerator rear wall, not uncommon [due to frequent usage ?] and assumed self-defrost feature would correct as usual. However/a barely-audible whirring noise instead developed and unit shut down...with no electrical smoke/odor evident. Now when plugged in, interior light comes on but no cooling in either freezer or refrigerator compartment; no sign/sound of operation at all. Eager for 'do-it-yourself' effort if properly directed [or availability of trouble-shooting manual]; but if effort thought to be 'impractical/uneconomical', please advise asap. Thank you in advance.

Refrigerators - Frost