If a part comes free from the build plate during a print, a buildup of filament can accumulate around the nozzle and heater block. To get the printer up & running again, preheat the extruder and remove the buildup using the tweezers in your toolkit. Then use the tweezers to clean up any material stuck to the heater block. Reducing the temperature to 180°C (for PLA) may help the debris come free in larger pieces.
To prevent that kind of failure, be sure to spray the build platform with 3DLAC between every print, and make sure your z-offset is well calibrated. Also confirm the part has a good contact surface with the build platform.