Refrigerator shut off for 3 months
Any moisture which was left inside from normal operation will likely develop into mold and/or mildew and create odors.
** how to cure it? **
Sometimes it can't be.
On a frost free model there are numerous air ducts throughout the appliance which can develop the problem, not to mention the insulation in the cabinet itself. Short of totally dismantling it and scrubbing or replacing all effected surfaces there isn't a lot you can usually do to correct such a condition once it has occurred.
If it hasn't developed too far, scrubbing the interior may help along with use of an odor absorbing material like baking soda or a commersial product linked below.
LINK > Fridge Aid® Deodorizer
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