Melon flowers like cantaloupe aren't compatible with the squashes (including pumpkins). You could try applying a phosphorous rich fertilizer but it's the beginning of August so depending on your location it may be too late in the season. Keep the phosphorous rich fertilizer in mind for next year though.

Mine just started setting lots of fruit in the last 1-2 weeks and I am definitely expecting pumpkins by the late October frost. They are small earlyish pumpkins though.

I might be ok yet as I have more flowers coming. I just hate to see the female flower wasted.

You could cross pollinate with zucchini or c pepo winter squash like acorn or delicata... assuming it is a c pepo pumpkin.

I don't have any of those growing in the garden right now. Thanks, though.