Код (vb.net):

Private Declare Function GetPrivateProfileString Lib "kernel32" Alias "GetPrivateProfileStringA" _
        (ByVal lpapplicationname As String, ByVal lpkeyname As Any, ByVal lpdefault As String, _
        ByVal lpreturnedstring As String, ByVal nSize As Long, ByVal lpfilename As String) As Long

Private Declare Function WritePrivateProfileString Lib "kernel32" Alias "WritePrivateProfileStringA" _
        (ByVal lpapplicationname As Any, ByVal lpkeyname As Any, _
        ByVal lpstring As Any, ByVal lpfilename As String) As Long

Public Sub writeINI(sINIFile As String, sSection As String, sKey As String, sValue As String)
    Dim n As Integer
    Dim sTemp  As String
    sTemp = sValue
    For n = 1 To Len(sValue)
        If Mid$(sValue, n, 1) = vbCr Or Mid$(sValue, n, 1) = vbLf Then Mid$(sValue, n) = " "
    Next n
    n = WritePrivateProfileString(sSection, sKey, sTemp, sINIFile)
End Sub

Public Function sGetINI(sINIFile As String, sSection As String, sKey As String, sdefault As String)
    Dim sTemp  As String * 256
    Dim nLength As Integer
    sTemp = Space$(256)
    nLength = GetPrivateProfileString(sSection, sKey, sdefault, sTemp, 255, sINIFile)
    sGetINI = Left$(sTemp, nLength)
End Function

Пример использования:

Код (vb.net):

'запись
writeINI App.Path & "\test.ini", "TestSection", "TestKey", txtValue

'чтение
txtValue = sGetINI(App.Path & "\test.ini", "TestSection", "TestKey", "None")
End Sub

Синтаксис:

writeINI [путь к файлу], [имя секции], [имя параметра (ключа)], [значение]

переменная = sGetINI([путь к файлу], [имя секции], [имя параметра (ключа)], [значение])