There's 2 main reasons for why a stream may have stopped
If you were watching a game and it went into half time for example, some streamers will stop the stream to save on bandwidth usage, hold tight and 9/10 the stream will come back on when the game restarts.
The stream just dropped, this is common with streaming online and can happen for a number of reasons, if this happens check the guide to see if there's any alternative links available, if there isn't don't worry, just let us know in the chat and we will replace the stream with a new one, we always try our best to get the most reliable and best quality streams available to us so hopefully this shouldn't happen too often if at all.