hello im having trouble with the radio used to contact the control tower or wingmen. it says the \ key us the radio but it never shows up.

Well it depends on your particular country keyboard. I'm in the UK and for me it is the # key. I think for other countries it is different again. Try #, try \, try ~, try |, try a few other keys.

The radio command menu comes up on the top right hand side of your screen.

Or change the key binding to a different key. Go into OPTIONS, INPUT, DEVICE = Keyboard, COMBAT, and about 30 lines down in the ACTIONS MAP you will see Communications Menu. For me it says KEY_BACKSLASH.