Allora sono tornato alle origini ma vedo che funziona bene....

codice:
 Public Function strconnection() As OleDbConnection        Return New OleDbConnection("Provider=Microsoft.ACE.OLEDB.16.0;Data Source=C:\COW-23\COW23\COW23\Database\Database_Generale.accdb")
    End Function
    Public strcon As OleDbConnection = strconnection()
    Public result As String
    Public cmd As New OleDbCommand
    Public da As New OleDbDataAdapter
    Public dt As New DataTable

Private Sub cbo_connetti_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cbo_connetti.SelectedIndexChanged
        Try
            Dim sql As String
            Dim cmd As New OleDbCommand
            Dim dt As New DataTable
            Dim da As New OleDbDataAdapter
            strcon.Open()


            sql = "SELECT * FROM PASSWORD_COLLABORATORE WHERE COLLABORATORE LIKE '%" & cbo_connetti.Text & "%'"
            cmd.Connection = strcon
            cmd.CommandText = sql
            da.SelectCommand = cmd
            da.Fill(dt)
            If dt.Rows.Count > 0 Then
                txt_password.Text = dt.Rows(0).Item("PASSWORD").ToString
                txt_id.Text = dt.Rows(0).Item("ID").ToString
            End If
        Catch ex As Exception
        Finally
            strcon.Close()
        End Try


    End Sub
ciao a tutti