I found the solution
These are how I did
1. To make single instance
Got to Project Properties at "Application" Tab, then checked "Make Single instance application".
2. To show previous instance
In "Application.Designer.vb" Select "StartupNextInstance" event add "e.BringToForeground = True"
eg.
Private Sub MyApplication_StartupNextInstance(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventArgs) Handles Me.StartupNextInstance
e.BringToForeground = True
frmGenerateProformaWeeklyLifting.NotifyIcon1.Visible = False
Me.MainForm.Show()
Me.MainForm.WindowState = FormWindowState.Normal
End Sub
It did work for my case.
Laxmikant_Yadav, thank you for your answer.