As TRON gets ready to migrate off the Ethereum blockchain, they have announced that there are certain instances where you can effectively lose all your TRX if you don't follow their procedure.
Don't panic. But make sure you understand what is happening and take the appropriate steps. This link tells more:
https://dailyhodl.com/2018/04/15/tron-alert-transfer-your-trx-or-risk-losing-it-all/