Why won't my gui work right?

Make sure that if you're doing this, if it's a server script make sure that

regenallcars=game.workspace.racercars racercars: remove()

should be

local regenallcars=game.workspace.racercars racercars: remove()

When local is added it makes sure that the gui is run all over the server, and not just for one player.

This script has too many mistakes in it to work properly and would have to be totally rewritten to work. I'd propose to learn the basics of scripting at this website: http://wiki.roblox.com/index.php?title=Special:RobloxLandingPage But I guess that the script is supposed to clean the workspace so I'll do this for you and explain everything.

for _, player in pairs(game.Players:GetPlayers()) do -- This is to do the same thing with all the players.
    player.PlayerGui.clean.serverclean1.MouseButton1Click:connect(function() -- This is an event that's being called when the TextButton is pressed.
        safetycopies = {} -- This is an empty table.
        for _, tobecopied in pairs(workspace:GetChildren()) do
            if not tobecopied:IsA("Terrain") and not tobecopied:IsA("Camera") then -- This checks whether the thing in the workspace is Terrain or a Camera. If it is not then the script will do the next step.
                table.insert(safetycopies, tobecopied:Clone()) -- This adds the clone of the thing to the table named safetycopies
            end
        end
        for _, toberemoved in pairs(workspace:GetChildren()) do
            if not toberemoved:IsA("Terrain") and not toberemoved:IsA("Camera") then
                toberemoved:Destroy() -- This cuts all connections and totally destroys the thing.
            end
        end
        for _, tobeplaced in pairs(safetycopies) do
            tobeplaced.Parent = workspace -- This adds the copied thing to the workspace.
        end
    end)
end