What causes a plant to suddenly droop and die

A customer has a question and I hope we can get some opinions on it, thanks

What causes a plant to suddenly droop and die was growing good yesterday this morning is hanging like it hadn’t been watered in years and it’s deep water culture- my girls are dying and I don’t know why

You got enough bubbles in the bucket what’s the temp of water what’s the ph in water what king of light what’s the ppm of the water need info I grow RDWC so I can’t help with out info fill out a support ticket so I can hell