Cotech weather station FT0203

I am new to this forum and may be in tge wrong place but here goes! I have a weather station, cotech FT0203. It has worked fine for three years, but i now have a problem. My indoor unit cannot see one of my outdoor sensors, the temperature/ humidity sensor. When i try to look for the sensor as per manual, i do not see the search icon on my indoor unit and the i get no readings. I am non tech and 80 + years old but have enjoyed this cotech unit. Thanks for any help