not local
local function click(player) game.Workspace.Countdown.BrickColor = BrickColor.new("New Yeller") player.Character.Head.Anchored = true wait(10) game.Workspace.Countdown.BrickColor = BrickColor.new("Lime green") player.Character.Head.Anchored = false while true do script.Player.PlayerGui.Tasksbar.t2.BackgroundColor3 = Color3.new("Lime Green") end end workspace.Task1.ClickDetector.mouseClick:connect(click)
It's not possible to change GUI's in a serverscript. Instead, make a RemoteEvent and FireClient(player) and make a localscript to change the GUI.