2 different celosia in the picture right?The one on the left(red one) has died :( . The big one on the right (celosia caracas) is not well.Flowers are dry and losing colour but the leafs are still green...ok.What to do because is a nice flower and i don't want to lose this one too.
Place it outdoors where it receives at least 1/2 day sun. Water when it begins to wilt and check the leaves for fine webbing indicating spider mites, a common problem with indoor plants.