How to access all players?

I was wondering, Does this script work? And how do you access all players for like teleporting all players and killing all players? (And how do you access a players backpack? Is it .backpack?) Script :

--[[ To leave comments type -- then your messsage.
	ex. --Add a timer. Put it next to the line you want me to add it to.
]]--
--[[VARIABLES]]--
timertext = script.Parent.Text
mappicked = script.Parent.hasPickedMap
intermissiontime = 20
timertime = 210
playersjoin = game.Players.NumPlayers
--[[FUNCTIONS]]--
--function countplayers
if playersjoin == 4 then
	--function intermission
	repeat 
		wait(1)
		intermissiontime = intermissiontime - 1
		timertext = intermissiontime
	until
	intermissiontime == 0
	--function choosemap
	timertext = "Choosing map..."	
	wait(1)	
	map = math.random(game.Workspace.Folder)
	timertext = map
	map:clone(game.workspace)
	map.Position = "0,0,0"
	--function teleplayers
	timertext = "Teleporting players..."
	--teleportplayers
	--function choosemurderer
	murder = math.random(game.Players)
	game.ServerStorage["Murderer Knife"]:clone(murder.Backpack)
end

Sorry for having a lot of questions, but also, how do you refresh a script, like, make the script reset and run again?

To access all the players you can do this:

local p = game.Players:GetChildren()

for i = 1,#p do
	p[i].CharacterAdded:wait()
	p[i].Character.Humanoid.Health = 0
end

This is the simplest version.

To reset a script, you could

1. Clone it and put in the script's parent, then remove() the script.

2. Make the entire thing a while loop.