Hi,

I’m sorry for your garden trouble. It’s hard to put in so much work and see so little result.

Corn can usually be picked about 20 days after tasseling, so I would hold out hope for that crop. The corn plants should be eight to ten inches apart, so these could be thinned. 

Beans have had a rough year with the extreme heat. Though your plants are short, they look healthy. They too are crowded and could use thinning to give plants more room. They may yet flower and bear. But you may want to plant something else.

The watermelon will not bear this year before frost, so that area would be good if you want to try a fall crop.  

Here’s a University of Minnesota fact sheet on planting for a fall harvest.

https://extension.umn.edu/planting-and-growing-guides/planting-vegetables-midsummer-fall-harvest

Next year dig in compost or manure to boost the soil quality before you plant.

Good luck!