In D&D5e, the game we are talking about, it´s different:
Prone (PHB, p242)
A prone creature’s only Movement option is to crawl, unless it stands up and thereby ends the condition.
The creature has disadvantage on Attack rolls.
An Attack roll against the creature has advantage if the attacker is within 5 feet of the creature. Otherwise, the Attack roll has disadvantage.
Ranged attackers have disadvantage against you, but if the enemies move into melee they attack you with advantage and you have disadvantage in all attacks.
