walkera master cp receiver and controller problem

Your rx might got demaged...

You can try to clear the fixed id from it with the bind plug to see if that helps, but probably it won't...

Were you using fixed-id? It shouldn't matter, but if so, make sure to reset the fixed-id,on the rx and tx. Set the Tx power as high as you can, and try to bind at close range. The most likely damage would be to the antenna connection on the receiver, and it is possible you could verify that by getting it to bind at near range/high power. If you have a Devo7e, then you don't have access to high power, so you may not have any luck getting it to bind. But even with a Devi8/10, it is still possible it won't work, in which case there isn't too much todo other than order a new Receiver board.