thanks but its not just minetown its every server now?!?

I use to be able to play minecraft multiplayer all the time... but now every time i try to connect to a server is says "Failed to login: Bad Login" Please Help! I have played it all the time but now i cant... <object class="emojione" data="https://resources.enjin.com/1489581540/themes/core/images/emojione/svg/2639.svg?0" type="image/svg+xml" standby=":(">:(</object>