Please Help! Plant Went Limp

So i am growing three babies (firtst grow) in my closet in dwc and things have gone really well. i am in the third week of flowering and everything looked really strong. I went into the room to check ph and one of my babies an afrodite femenized was limp as could be. this plant was immaculate yesterday. i watered last night with 2/3 nutes. what the hell happened. what should i do? should i wait till the lights come on and see if it stretches back towards the light, rewater (wich im scared to do since i just did!) or what? any help is greatly appreciated

well i saved the two plants that were having trouble. i rinsed the roots lightly in ph correct water and cleaned the resevior and tubing and airstones. I added .03 h2o2 at 5ml per gallon of water fortwo days and they recovered and are now standing erect. great huh? not reallly cause now my four foot kandy kush is doing the same thing except not laying over. all shoots with bud are sturdy but fan leaves are turning purple at the stem and now are drooping dramatically. the roots looked better than the others. i am trying the same steps to help it recover. i am in week four of flowering. dwc with 8 inch airstones and have been using fox farm tiger bloom. room temps are 77 while sleeping and usually between 79 and 81 with the lights on. humidity is always between 48 and 50 %. water temps are at 70 degrees. should i move my lights farther from the plant itself if this is a heating issue? the plant is green with no damage really being done to the fan leaves, they are just drooping and when i say drooping i mean completely limp. anyone have this happen to them? any help would be apreciated!!!

H2o2 can burn your roots!! get it off, also 85 is too warm for H2o2 ! 75°C tops! you need Hygrozyme or beneficial bacteria products.