Tim,
If it pulled out of the rx, you'll need to take the case apart. Look at the case and you'll see a hole in it where the wire came out. Once you take the case apart, look in that corner of the pc board, you'll more then likely see the remains of the lead there. The lead goes in a small hole on the board, loops over and then is soldered to the board. If the lead broke off flush, remove a tiny section of the insulation on the antenna, tin it with solder, and resolder it to the board. If it broke off long enough, just solder the 2 ends together and cover it with a piece of shrink wrap, and you are good to go.