How do I handle a long gap on my résumé? after 13 years as a marketing coordinator

I have been out of work for 3 months and worry about the gap. I have read a lot of threads here and could not find my exact situation. I have done some volunteering and a course during that time. How did you handle it on your résumé?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.

I listed the volunteering and course under the same dates and kept the explanation to a sentence in the cover letter.