Fix ROKU device problems by clearing the cache. This is how to clear Cache in your ROKU device every time you have a glitch with sound, frozen apps, buffering TV, black screen, or whenever your Roku device doesn't work properly: Press the Home button 5 times Up button 1 time. Rewind the button 2 times. Fast Forward button 2 times Wait for your device to reboot. If this doesn't work for you, unplug your TV for 1 minute. Plug it back in and repeat the process.