Agree with Juanitos Peppers, looks like "Damping Off", see encircled area of your plant below....Note healthy to dying? Click here for help.> prevent damping off disease

It is not uncommon for seed leaves to drop after it gets it first few sets of true leaves but given your recent loss I wouldn't rule out other issues as the culprit.

I would agree with damping off, and the yellowing you mentioned agrees with this and makes me think overwatering, except you had mentioned the heat. If you are growing these seedlings in seed starting trays outdoors, they can dry out extremely quickly on very hot and sunny days and kill the plants, and damping off would be unlikely in hot and dry weather outdoors.

Can you provide more info.. pot size, potting medium, watering, indoor/outdoor, weather outdoors if growing outdoors, supplemental lighting indoors etc?

Thank you for the replies . After a few days more seedlings started to topple over, and more signs of damping off was evident on the poor seedlings.

All the pepper seeds were started on a plastic container and were just transplanted to basic plastic cups (poked some holes at the bottom). I just started to grow these peppers as some form of a hobby, and was not really serious at first. But as soon as I saw them sprout it made me all giddy and seeing them grow made me even happier. With all that's happening, I've researched more about how to properly care for pepper plants. And the main cause of all this is the wrong soil that i used. I just used basic garden loamy soil from my backyard thus soil compaction IS an issue, and other possible problems that can arise from improper choice of soil. I've learned my lesson and will properly take care and do proper research for my future seedlings from now on.

My question now is is it still possible to save some of my healthy looking seedlings if I transplant them to the proper form of soil? Or do I just give up on them and start over with the right form of potting medium? As of now I diluted some of the chamomile tea I was having earlier and sprayed some on the soil (did a google search that it could save seedlings from the fungi w/c causes damping off) as some form of a temporary solution. I appreciate all the help that I received and would still get .

you can wait and see. might be best to just throw all that garden soil back outside though, in case there is anything else lurking in it. A spray of tea won't do much to stuff that's down under the first few cm of soil.

a proper draining soiless medium(pro-mix,coco,berger,etc) and some dyna gro foliage pro and you will be good to go.

At this point, I would just start over with fresh containers and fresh soil. Clean up all the tools you have been using. It is just a set back. It isn't the end of a season. Also, make sure you are not over watering. That is one of the primary causes of damping off. Providing the seedlings with some circulating air will also help a lot.

Agree with above, but I believe that any that aren't showing symptoms CAN be saved.

Some remedies and/or "shoulds" to prevent or stave off damping off---

Chamomile tea as mentioned above

4 parts water to 1 part hydrogen peroxide 3%

Mosquito dunks

sprinkling cinnamon around seedlings to repel fungus gnats

"should" bottom water

sterilize media before sowing

"should" definitely run a small fan for circulation

"should" use THIS method when watering --- water thoroughly when needed, THEN let soil get almost bone dry before watering thoroughly again. You "should"(if you can) keep this type of watering go on for the life of the plant, but definitely as a seedling.

Good luck.

Kevin

Just an update, I want to thank everyone on this thread as majority of my pepper plants were saved! (Some died due to transplant shock lol) they are now looking happy and healthy! :)

Yahhhh, the season is saved.

That's awesome! Any updated pics you want to post?