Maytag mbf2258xewa refrigerator bottom mount freezer has frost on the channels, walls, icecubes and items in freezer. Also the light does not turn on.

You have a bad defrost heater, defrost t-stat, and/or the defrost timer, too. Since they all go out at about the same time it's best on these small units to replace all three and it will be good for a long time if you clean the coils well and defrost it before doing any work on it and wash it out well, too. Here's some manuals: https://dl.dropbox.com/u/8010163/Maytag%20Refrigerators.zip