Reset countdown

how to reset countdown after hitting 0

where your countdown value stored?, and show the code that decreases it

basically when timer changes you need to check if countdown <= 0,

time.Changed:Connect(function()
    if time <= 0 then -- or if time.Value <= 0
         time = 60 -- number that you want
    end
end)

or you can do it right in the countdown cycle after decreasing value

repeat -- your cycle
    time = time - 1 -- decreasing

    if time <= 0 then 
       time = 60 -- number that you want
    end

    task.wait(1)
until false