My battery went dead and now my key fob won't unlock my doors what do I do?

Car battery? or fob battery? If the fob battery is out This You Tube video may give you some help https://www.youtube.com/watch?v=ZzmNt5R3Q5A

Fob won’t detect on my 2018 rav 4 until I touch the button with the fob.

If your Rav4 (mine is a 2015) stops recognizing the key fob that came with the car and won't start, try the following: 1. Use the key fob end to push the start button (do NOT put your foot on the brake as if to start the car). The dash should light up. 2. Push the start button with the key fob again but this time continue to hold the start button in with the key fob (still no foot on the brake). Your control screen should show a progress line progressively moving from left to right as the vehicle reacquaints itself with the key fob. 3. When the process has completely cycled, take the key fob away, step on the brake, push the start button, and hopefully the car will now start. NOTE: I don't think this would work to program a new fob that did not come with the car when it was purchased. Only to reacquaint an existing fob. Hope this helps!