Refrigerator and Freezer not cooling and Evaporator coil in Fridge side is frozen

My freezer first started warming up and melting the ice in the ice maker and my Fridge would also heat up. I notice the Ice build up on the Fridge Evaporator Coil due to the fan hitting the Build up of ice on it. I unplugged it and allowed to Thaw and it work fine for another 2 Weeks and again the freezer and Fridge warmed up and the fan started hitting ice on the Evaporator coil. I have read some reviews and and had some different suggestions. Thanks for reading my Post. Mike