Mine are in desperate need please help,
Soak them in a bathtub or a large garbage bag or a small kids pool in warm sudsy water with dish soap for a few hours. Scrub off with a dishcloth and a brush. They will look like new.
This is strong so do it outside. Keep your face away from it before and after. Put them in a garbage bag with 1/4 cup of ammonia. Seal bag, and leave overnight. The next day hose them down. You should now be able to remove the rest quickly, with a soapy Brillo pad, or regular steel wool and dish soap. After they are clean cover them with foil. Most stove instructions say not to cover them, but I don't notice a difference with cooking, and it is so much easier to clean them afterwards.
Most self cleaning oven manufacturers will tell you to remove the oven racks while cleaning the oven.... they say that the high temperature will cause the chrome to discolor.... and it does... and it will not clean up or be bright again... (I left one of my racks in while cleaning up some old cast iron... but I was aware that they might change color when I did it) they also tell you to remove the lower drawer and its contents while running the cleaning cycle
I like to soak mine in the sink with Dawn dish soap and ammonia and VERY hot water (at least a kettle of boiling)
I have also put the racks in a heavy garbage bag, sprayed them with Easy Off, and let set out in the sun for several hours.... scrub with a small wire brush or Brillo pad if needed
Place them in a garbage bag and spray with oven cleaner. Let sit over nite. Scrub and hose off the next day