i am writing simple program to get the sorted date . But it does not work.

Dim filepath As String = FileStr
Dim directoryPath As String =      System.IO.Path.GetDirectoryName(filepath)
for Each file As String In System.IO.Directory.GetFiles(directoryPath)
Dates = {
Date.Parse(System.IO.Path.GetFileNameWithoutExtension(file))
        }.ToList
Next
Dates.Sort()
ComboBox1.DataSource = Dates

It only show one date ..where there are more than 10 date. and also the loop is working

I declare the List as global

You're replacing the content of your list in every loop

Dim filepath As String = FileStr
Dim directoryPath As String =      System.IO.Path.GetDirectoryName(filepath)
for Each file As String In System.IO.Directory.GetFiles(directoryPath)
    Dates.Add(Date.Parse(System.IO.Path.GetFileNameWithoutExtension(file)))
Next
Dates.Sort(AddressOf SortDate)
ComboBox1.DataSource = Dates

UPDATE: Sorting issue

Then as a seperate function add:

Function SortDate(ByVal a As DateTime, ByVal b As DateTime)
    Dim result As Integer = a.Year.CompareTo(b.Year)
    If result = 0 Then
        a.Month.CompareTo(b.Month)
        If result = 0 Then
            a.Day.CompareTo(b.Day)
        End If
    End If
    Return result
End Function