DIAGNOSIS The infrared receiver on the purifier's control panel is blocked or faulty, or the remote is damaged.
FIX First, test the remote. Use your phone's camera in selfie mode. Point the remote's LED at the camera and press a button. You should see a purple light flash on your screen. If not, the remote is dead.
IF THAT DIDN'T WORK If the remote works on camera, the IR receiver on the purifier is the issue. Ensure nothing is blocking the dark translucent window on the control panel. Wipe it clean. The receiver is soldered to the main board—if damaged, the board needs service.
HEADS UP The remote is not essential for operation. All core functions are on the unit's buttons. Replacement remotes are available from Winix.