A/C not blowing, only on "recirculated" setting

What is your question?

I have a manual lever that slides from letting in outdoor air to changing to recirculated air. I know it is more efficient, on hot days, to let the car get a little cool and then start using recirculated air. This quite suddenly stopped working. Most repair blogs I've found talk about the A/C in general - which seems to be working. I'm not experienced car repair person, but do have other repair experience. I am hesitant to spend tons of money on something that sounds like it should be simple.