[قناص المدينة]

استخدم هذه الدالة

Public Shared Function RandomNumStr(ByVal intStrLength As Integer) As String

Dim chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"

Dim intLength As Integer = intStrLength - 1

Dim stringChars = New Char(intLength) {}

Dim random = New Random()

For i As Integer = 0 To stringChars.Length - 1
stringChars(i) = chars(random.[Next](chars.Length))
Next

Dim finalString = New [String](stringChars)
Return finalString
End Function

وفى اى حدث ضع هذا الكود

TextBox1.Text = RandomNumStr(5)