How to anchor player when TextButton clicked?

Hey peeps. So I've been having some trouble anchoring a player once the text button is clicked. I've tried using this script:

local part = script.Parent
local db = false

part.MouseButton1Click:Connect(function(clicked)
	local human = clicked.Parent:findFirstChild("Humanoid")
	if human then
		db = true
		human.Parent.UpperTorso.Anchored = true
		wait(20)
		human.Parent.UpperTorso.Anchored = false
	end
end)

But it doesn't work. The output says:

Players.Paradoa.PlayerGui.MainMenu.TextButton.LocalScript:5: attempt to index nil with 'Parent'

So this is a common mistake with new scripters, but case does matter, and also don't forget to get your hierarchies correct.

So you don't even need this line but I do need to point out your error in it:

local humanoid = clicked.Parent:FindFirstChild("Humanoid") --first F in this function always must be capitalized

Your fixed script:

local part = script.Parent
local human = game.Players.LocalPlayer
local db = false

part.MouseButton1Clicked:Connect(function() --you need to make sure that you know what the event you choose to use returns something.
    if not db then --if you don't check for your debounce, then it won't work
        db = true
        human.UpperTorso.Anchored = true --human.Parent would've been workspace, so unless you have a part called UpperTorso inside the workspace, this wouldn't have worked.
        wait(20)
        human.UpperTorso.Anchored = false
        db = false
    end
end)

If this answers your question, then mark it as accepted, otherwise, let me know if you have any further questions about this.

I'm not sure what the parameter for MouseButton1Click is, because I've never used it, and it doesn't show it on the wiki. However, I assume you're just trying to access the local player, so just use that.

local player = game:GetService("Players").LocalPlayer
local part = script.Parent
local db = false

part.MouseButton1Click:Connect(function()
    local human = player.Character:FindFirstChild("Humanoid") --note the capital F
    if human then
        db = true
        human.Parent.UpperTorso.Anchored = true
        wait(20)
        human.Parent.UpperTorso.Anchored = false
    end
end)

GUIs have to be local scripts. If you use GUIs on a script, it will likely either do nothing or return nil. So you have to use Remote Events. Any mistakes and I will put them in --comments. Put the Remote Event in ReplicatedStorage.

Local Script

local textButton = script.Parent.TextButton --Put your local script BELOW the ScreenGui.
local db = false
local remoteEvent = game.ReplicatedStorage.RemoteEvent

textButton.MouseButton1Click:Connect(function() --You do not need the click parameter.
	if not db then --You do not need the humanoid as a player is required to click.
		db = true
		remoteEvent:FireServer()
		wait(20)
		--db = false --I assume you want it once, but remove the comment if you wanna do it multiple times.
	end
end)

Server Script

local remoteEvent = game.ReplicatedStorage.RemoteEvent

remoteEvent.OnServerEvent:Connect(function(player) --The player parameter has to be first, and we're sending the player.
	local character = player.Character
	character.HumanoidRootPart.Anchored = true --HumanoidRootPart is recommended.
	wait(20)
	character.HumanoidRootPart.Anchored = false
end)