Accidentally i left my progesterone suppositories out of the refridgerator for 12 hours. they did not melt. are they no more useful?

Depends on brand: Likely still okay since has not melted, however different brands have different storage recommendations/requirements. I suggest you call your pharmacist or the manufacturers customer service number, as they can best determine if they can still be used or should be discarded. Take care!

Should be fine: Being left out at room temperture (68-75 deg F ) should not make them ineffective. Just put them back in the refrigerator for 20-30 minutes and then insert one of them vaginally as directed.