Manage Case Statement with (Int, long, short, double.....) I have the following case statements that has to be modified to fit these cases:
Dec, Double, Int, Long, Short, Date, and String.

Please let me know if there is an easier way to handle this rather than repeating the following (slightly modified for each case):

Case GetType(Integer)
    If String.IsNullOrEmpty(c.Text) Then
        list.Add(CInt(0))
    Else
        Try
            list.Add(CInt(c.Text))
        Catch ex As Exception
            WriteAudit(ex, True)
            Dim intValue As Integer
            If Not Integer.TryParse(c.Text, intValue) Then
                c.Text = c.Text.Substring(0, c.Text.Length - 1)
                MessageBox.Show("Please Enter Only Integer Values Here")
            End If
        End Try
    End If
For value types (i.e. all your types except String) you can use the Convert.ChangeType method:

list.Add(Convert.ChangeType(c.Text, theType))