Make sure you are operating the remote control within the reception angle and range of the projector. See Remote Control Operation.
Check to see if a button on the remote control is stuck down, causing it to enter sleep mode. Release the button to wake the remote control up.
Strong fluorescent lighting, direct sunlight, or infrared device signals may be interfering with the projector's remote receivers. Dim the lights or move the projector away from the sun or interfering equipment.
If available, turn off one of the remote receivers in the projector's menu system, or check if all the remote receivers were turned off.
If you assigned an ID number to the remote control to operate multiple projectors, you may need to check or change the ID setting.
If you lose the remote control, you can order another one from Epson.