To go in reverse, you back up. If you reverse your position, you suddenly take the opposite side of the argument. If you reverse your fortunes, your bad luck turns good, or your good luck turns bad. Oops.
The Latin word revertere means “turn back.” To reverse means to turn back, take the opposite direction, go the other way. Many things can be reversed: you can reverse a decision, you can reverse a car — by putting it in the gear called "reverse." You can reverse a political argument, a promotion, even some surgical procedures, but you can never reverse the steady progress of time, no matter how many Botox injections you get.