VB.NET; My code has been vanished

Mysteriously! my code has been vanished but its working properly. It had some code for SQL Insertion and connectionstring, all is working properly form is executing as normal and sql data table shows data too....but there is no code behind the form only following lines are in the "Registration.vb" file. Can anyone tell me what's the problem?

Private Sub btn_Register_Click(sender As Object, e As EventArgs) Handles btn_Register.Click
    c()
End Sub