Try

Dim file As String = Server.MapPath("./wmplayer.exe")

It may work.

It still can't work after trying both methods. It still returns 'The system cannot find the file specified'  and highlights
Dim p As Process = Process.Start(file). Kinda desperate here, Someone pls help!!

Anyway here is the stack trace.
[Win32Exception (0x80004005): The system cannot find the file specified]
   System.Diagnostics.Process.StartWithShellExecuteEx(ProcessStartInfo startInfo)
   System.Diagnostics.Process.Start()
   System.Diagnostics.Process.Start(ProcessStartInfo startInfo)
   System.Diagnostics.Process.Start(String fileName)
   webvault.WebForm1.Button2_Click(Object sender, EventArgs e) in c:\inetpub\wwwroot\webvault\WebForm1.aspx.vb:69
   System.Web.UI.WebControls.Button.OnClick(EventArgs e)
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
   System.Web.UI.Page.ProcessRequestMain() +1292

Dim file As String = Server.MapPath("~/Monitor.exe")

If Not System.IO.File.Exists(file) Then

End If

Dim info As New ProcessStartInfo(file)

'ProcessStartInfo(file)

' Redirect output so we can read it.

info.RedirectStandardOutput = True

'To redirect, we must not use shell execute.

info.UseShellExecute = False

' Create and execute the process.

Dim p As Process = Process.Start(file)

' Send whatever was returned through the output to the client.

'Response.Write(p.StandardOutput.ReadToEnd())

End Sub