a simple 3 minute program

Ok heres the new code i added comments to make it more readable, and if you look you'll see where i need help.

AppTitle "3minutes"

Graphics 300,100,1,2
SetBuffer BackBuffer()

;some veriables
s=31

t=20

second=0

minute=0

start=False

secondtimer=MilliSecs()

;loads the sound.
sound = LoadSound("Ungodlysound.wav")

While Not KeyHit(1)
Cls

;clock and timer code:
If MilliSecs() > secondtimer+1000 Then
second=second+1
secondtimer=MilliSecs()
End If
If second>59 Then
minute=minute+1
second=0
End If
If minute=3 Then
minute=0
PlaySound sound
second=0
End If

;stop and start switchs
If KeyHit(s) And start=False
start=True
Else If KeyHit(t) And start=True
start=False
End If

;atempt to make the start/stop switch stop and start...
If start=False
; What goes here???
; nothing i'v tried works ...
; Help!
End If

;display the switch status
If start=False
Text 20,60,"Press 'S' to Start the timer."
Else If start=True
Text 20,60,"Press 'T' to Stop the timer."
End If

;some other displays
Text 60,80,"Press ESC to Exit."
Text 130,30,minute+":"+second

;delays the program updating every half a second. slows down the lagg big time
Delay 500

;flips the buffer, ends the loop and when it ends it ends the program.
  Flip
Wend
End

Notice the problem, i got the switch working, it just needs somthing to stop the timer, so basicly, what code stops a timer?

;atempt to make the start/stop switch stop and start...
If start=False
; What goes here???
; nothing i'v tried works ...
; Help!
End If