How can i check gave directory is wright or not?in brows input.

#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <process.au3>

$COMPANY_NAME = "HM-LINK" ; name of the pppoe icon, friendly description
$SERVICE_NAME = "HM" ; name of the pppoe service configured in NAS/Mikrotik
Local $font
$DELAY = 300
$frmInformation = GUICreate($COMPANY_NAME, 287, 230, 193, 115)
$btnOK = GUICtrlCreateButton("&GO!", 208, 200, 68, 25, 0)
$btnbrw = GUICtrlCreateButton("&Browse", 208, 164, 68, 25, 0)
$txtbrw = GUICtrlCreateInput("", 118, 164, 80, 21)
$lblbrw = GUICtrlCreateLabel("Select Icon:", 16, 169, 80, 17)
GUISetState(@SW_SHOW)
While 1
$uMsg = GUIGetMsg()
Switch $uMsg
Case $btnbrw
Local $message = "Hold down Ctrl or Shift to choose multiple files."

Local $var = FileOpenDialog($message, @WindowsDir & "\", "Icon (*.Ico;*.bmp)", 1 + 4)

If @error Then
MsgBox(0, "", "No Icon chosen")
Else
$var = StringReplace($var, "|", @CRLF)
EndIf
ControlSetText($COMPANY_NAME,"","[CLASS:Edit; ID:11]",$var)
Case $btnOK
$txtbrwr = GUICtrlRead($txtbrw)
If StringLen($txtbrwr)=0 Then
MsgBox(64,$COMPANY_NAME &" 03216592390","Please Choose Hm5 Icon.")
Else
$txtbrwr = GUICtrlRead($txtbrw)
ExitLoop
EndIf
Case $GUI_EVENT_CLOSE
Exit
EndSwitch
WEnd
GUISetState(@SW_HIDE)
Run("control ncpa.cpl")
Sleep($DELAY)
WinClose("Network Connections")