If your Cable or Bell box is not working, try some of the following:

First, try manual control. Pressing the power button on the box should turn it off and on. The Channel up and down buttons should work also.

No= reboot box. It is most likely locked up. Pull power cord and plug back in. After a few minutes, it should reload software and work again.

Yes, but still no control= check if IR emitter is flashing red when you press buttons on remote control, and that it is still attached to the box.

If emitter is fell off, that is the problem. The emitter needs to be put over the IR receiver window on the box.  This is the spot on the box that receives remote control signals. 

Using the flash on your phone directed at the front of the cable box will help you locate this receiver. Looks like a round hollow opening behind the black plastic facing on the box.

If you press buttons on remote control like channel up or down, you can test the correct spot by moving the emitter around each time.

Once you found the "Spot", use hot glue or scotch tape if nothing else, to hold in position.