How to keep dead characters?

Not one to spoon feed. Please show us your current code to see what you have tried to do already. But anyways here you go put this as a normal Script in StarterPlayer.StarterCharacterScripts

local debrisservice = game:GetService('Debris')
local body = script.Parent
local player = game.Players:GetPlayerFromCharacter(script.Parent)
local humanoid = body:WaitForChild('Humanoid')
local bodydisposal = 30 -- Time till body is removed set to a high number if you dont want it to despawn

humanoid.Died:Connect(function()
	if player ~= nil and humanoid ~= nil then
		body.Archivable = true
		script.Parent = game:GetService("ServerScriptService")
		local cloneChar = body:Clone()
		cloneChar.Name = player.Name.."'s Deadbody"
		if game:GetService("Workspace"):FindFirstChild(cloneChar.Name) then
			game:GetService("Workspace"):FindFirstChild(cloneChar.Name):Destroy()
		end
		wait(0.1)
		cloneChar.Parent = game:GetService("Workspace")
		local rootPart = cloneChar.HumanoidRootPart or cloneChar.Torso
		local clonedHumanoid = cloneChar:FindFirstChildOfClass("Humanoid")
		cloneChar:MoveTo(rootPart.Position)
		rootPart.Orientation = Vector3.new(90,0,0)
		clonedHumanoid.PlatformStand = true
		clonedHumanoid.DisplayDistanceType = Enum.HumanoidDisplayDistanceType.None
		clonedHumanoid.HealthDisplayType = Enum.HumanoidHealthDisplayType.AlwaysOff
		for i, v in pairs(cloneChar:GetChildren()) do
			if v:IsA("BasePart") then
				v.Anchored = false
				v.CanCollide = false
			end
			if v:IsA("Script") or v:IsA("LocalScript") then
				v:Destroy()
			end
		end
		if cloneChar:FindFirstChild("ForceField") then
			cloneChar.ForceField:Destroy()
		end
		body.Parent = game:GetService("ServerStorage")
		debrisservice:AddItem(cloneChar,bodydisposal)
		debrisservice:AddItem(script,bodydisposal)
		wait(1)
		if rootPart.Orientation ~= Vector3.new(90,0,0) then
			rootPart.Orientation = Vector3.new(90,0,0)
		end
	end
end)