Hello again,
i've a small problem. After entering the data from Form2 I don't know how to refresh Form1 automatic after closing Form2
For refresh Data I use ShowData()
Thanks for any help or advises

Code:
Imports System.Data.OleDb
Public Class Form1
    Public dbconn As New OleDbConnection
    Dim adt As New OleDbDataAdapter
    Dim ds As New DataSet

    Dim datatable As New DataTable
    Dim cmd As New OleDbCommand

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        dbconn.ConnectionString = "provider=microsoft.jet.oledb.4.0;data source=key.mdb"
        showData() 'show database values in datagridview
        Button1.Text = "Give"
        Button2.Text = "Return"
    End Sub
    Public Sub showData()
        Dim dbcommand As String
        dbcommand = "SELECT * FROM keys"
        adt = New OleDbDataAdapter(dbcommand, dbconn)
        datatable = New DataTable
        adt.Fill(datatable)
        DataGridView1.DataSource = datatable
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim form As New Form2
        form.Button3.Text = "Add"
        dbconn.Dispose()
        dbconn.Close()
        form.ShowDialog()
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Dim form As New Form2(CInt(CStr(DataGridView1.CurrentRow.Cells(0).Value)))
        form.Button3.Text = "Edit"
        form.ComboBox1.Text = DataGridView1.CurrentRow.Cells(1).Value.ToString()
        form.TextBox2.Text = DataGridView1.CurrentRow.Cells(2).Value.ToString()
        form.TextBox2.Enabled = False
        form.ComboBox1.Enabled = False
        dbconn.Dispose()
        dbconn.Close()

        form.ShowDialog()
    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        showData()
    End Sub
End Class
Code:
Imports System.Data.OleDb
    Public Class Form2
        Dim provider As String
        Dim dataFile As String
        Dim connString As String
        Dim sql As String
        Dim myconn As OleDbConnection = New OleDbConnection

        Private currentRowIdentifier As Integer

        Public Sub New()
            ' This call is required by the designer.
            InitializeComponent()

            ' Add any initialization after the InitializeComponent() call.
        End Sub

        Public ReadOnly Property CurrentId As Integer
            Get
                Return currentRowIdentifier
            End Get
        End Property
        Public Sub New(ByVal pIdentifier As Integer)

            ' This call is required by the designer.
            InitializeComponent()

            ' Add any initialization after the InitializeComponent() call.
            currentRowIdentifier = pIdentifier
        End Sub


        Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
            myconn.Close()
            Me.Close()
        End Sub

        Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
            ComboBox1.Items.Add("Office1")
            ComboBox1.Items.Add("Office2")
            ComboBox1.Items.Add("Key1")
            Label1.Text = "Key"
            Label2.Text = "Give"
            Label3.Text = "Name"
            Label4.Text = "Return"
            TextBox0.Visible = False
        End Sub
        Sub Add()
            Dim main As New Form1
            provider = "provider=microsoft.jet.oledb.4.0;data source=key.mdb"
            connString = provider & dataFile
            myconn.ConnectionString = connString
            myconn.Open()
            Dim str As String
            str = "Insert into keys([1], [2], [3], [4]) Values (?,?,?,?)"
            Dim cmd As OleDbCommand = New OleDbCommand(str, myconn)
            cmd.Parameters.Add(New OleDbParameter("key", CType(ComboBox1.Text, String)))
            cmd.Parameters.Add(New OleDbParameter("give", CType(TextBox2.Text, String)))
            cmd.Parameters.Add(New OleDbParameter("name", CType(TextBox3.Text, String)))
            cmd.Parameters.Add(New OleDbParameter("return", CType(TextBox4.Text, String)))
            Try
                cmd.ExecuteNonQuery()
                cmd.Dispose()
                main.showData()
                myconn.Close()
            Catch ex As Exception
                MessageBox.Show("Error")
            End Try
            Me.Close()
        End Sub
        Sub Edit()
            Dim main As New Form1

            If String.IsNullOrWhiteSpace(myconn.ConnectionString) Then
                myconn.ConnectionString = "provider=microsoft.jet.oledb.4.0;data source=key.mdb"
            End If
            If myconn.State = ConnectionState.Closed Then
                myconn.Open()
            End If

            If ComboBox1.Text <> "" And TextBox2.Text <> "" And TextBox3.Text <> "" And TextBox4.Text <> "" Then

                sql = "UPDATE KEYS SET [1] = @key, 2 = @give, 3 = @name, 4 = @ret WHERE id = @id"

                Dim cmd As OleDbCommand = New OleDbCommand(sql, myconn)
                cmd.Parameters.AddWithValue("@key", ComboBox1.Text)
                cmd.Parameters.AddWithValue("@give", TextBox2.Text)
                cmd.Parameters.AddWithValue("@name", TextBox3.Text)
                cmd.Parameters.AddWithValue("@ret", TextBox4.Text)
                cmd.Parameters.AddWithValue("@id", currentRowIdentifier)

                Dim Affected As Integer = 0
                Try
                    Affected = cmd.ExecuteNonQuery()
                    If Affected = 1 Then
                        MessageBox.Show("Updated")
                    Else
                        MessageBox.Show("Updated failed")
                    End If
                    cmd.Dispose()
                    myconn.Close()
                    Me.Close()
                Catch ex As Exception
                    MessageBox.Show($"Error: {ex.Message}")
                End Try
            Else
                MessageBox.Show("Empty fields!")
            End If
        End Sub

        Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
            If Button3.Text = "Add" Then
                Add()
            End If
            If Button3.Text = "Edit" Then
                Edit()
            End If
        End Sub
    End Class