Needing help

Plants are sick & cannot figure it out

Can't see enough of the plant to tell for sure but it looks a lot like a bad fungus gnat infestation. Do you see a lot of little flies buzzing around when you move the branches and leaves? Look down at the top of the growth media too. If it stays wet on top the little buggers just love it. If you see them cover the top with diatomaceous earth and scrape it in a little.
What are you growing in? How often do you water? What are you feeding them? Also have you done and foliar sprays?