my betfair android mobile app stopped working and when I tried to download it again there was only a black app for TRADEFAIR

Hi, there.

What app are you using? Is it the Exchange or the Sportsbook? Are you on Android or iOS? There is an issue with the Android Sportsbook app at the moment which is being investigated - so if this is what you're trying to use, you may have better luck in going via the mobile site on your browser, by going to www.betfair.com/sport.