My IR remote doesn't work in the dark how do I fix it

Change the batteries.

Remotes work with infra red light, light or dark should not have an effect. You can not see infra red with the naked eye but it will show up when picked up with a video camera. I used to test mine using a video camera set to be viewed on my TV, and I could see the light flash when I pressed buttons. If your using the remote differently in the dark than in the light (in bed for instance) make sure that your not somehow blocked from that position. When in bed I used to have to hold my remote up in the air because the table it was on blocked the view to the receiving window on the TV. It also worked if I aimed it at the ceiling instead of directly at the TV.