Hello, and welcome to the Forums.
I presume you tried watering the plant and it did not perk up. If it doesn't respond to water, then there is some type of wilt or rot disease involved. If sthe whole plant is wilting from disease, then it is probably too late to save this plant. What you want to do now is dispose of the plant so that it won't infect any other plants. The soil in the container is also like to be infected and should be composted or at least left fallow. If you do want to reuse the soil, use it to grow a plant that is not related to pumpkins or squash (Cucurbita spp.) or anything else in the Squash Family (Cucurbitaceae).