Started melon seeds indoors, couple sets of true leaves, now wilted

[Sweets777]

Seedling leaves wilting

I've shared some pictures and a video of my melon seedling which have all wilted seemingly overnight...

I've been keeping these seedlings indoors at 75f since germination, but they did spend two hours at 60-65f a couple days ago. Could this have been the cause or is this typical of over watering, under watering, or both? I feel it is not damping off as I lost a few of these to damping off and there was noticeable damage at the base of the stem.

Could this have been caused by leaving a strong vinegar/water solution open on the room overnight? Was doing some deep cleaning and mistakenly left it in there which cause a strong odor. All plants all got similarly wilted overnight which makes me feel like it's something environmental outside which is why I thought I might've gas bombed them with the vinegar vapors, if that's even a thing?

 

[oneeye]

Take the pot and tip the plant out gently and get a feel of the roots. When they are wilted, that's the time to tip it out and get a look and a feel of the roots. All that being said, i don't think its a watering issue or vinegar/water solution that caused wilting. I think they are not getting enough sun.

Watermelons require full sun for proper growth. For full sun, choose a place where the watermelons will receive eight to 10 hours of direct sunlight daily. For plants to remain healthy and productive, as they get bigger they need more Sun.

 

[headfullofbees]

It is really difficult to get watering of cucurbits correct, and at that stage they need soil that's barely damp to avoid the possibility of rootrot.
I'm not a big fan of watering from underneath, but cucurbits are the exception.
It may be that your plants are still saveable, if you put the pots into lipped saucers & water the saucer once a week, but the roots may be too far gone, and nothing will save them in that case.
If you have time and space, start again, and if your original plants do make it, choose which are best at planting time or give the excess plants away.