Is there anything to restore my dieffenbachia?
I gave it to you already. Do I have to write it all over again. This would be the 3rd time. If you don't have it, forget it!
Since I, personally, don't recall seeing your question before, I can only apologize to you that you didn't get the information you needed when you asked earlier. I'm going to say some general things about dieffenbachia, and if they don't cover your problem, please feel free to write to me personally with your question. This article might address your situation: https://www.gardeningknowhow.com/houseplants/dumb-cane/growing-dumbcane-dieffenbachia.htm
The problem most likely to afflict dieff is root rot from soil that stays too wet. Testing the soil moisture in the bottom of the pot will remedy this. You can use a moisture meter, or a wooden skewer as if testing a cake. The soil should be very slightly damp before you water again.
If the roots have been damaged, move the plant into higher light to promote increased water evaporation and root growth.