Set No access (ReadLocked) Programmatically for a Site Collection (SPSite)

SPUser

user = SPContext.Current.Web.CurrentUser;

//NOTE: The account which runs the application pool needs to be a farm administrator

SPSecurity.RunWithElevatedPrivileges(delegate()

{

using (SPSite site = new SPSite("Your Site Utl"))

   {

     site.WebApplication.FormDigestSettings.Enabled = false;

     site.AllowUnsafeUpdates = true;

     site.WriteLocked = false;

     site.ReadOnly = false;

     site.LockIssue = "The site was disabled by: " + user.Name + " (e-mail: " + user.Email + ")";

     site.ReadLocked = true;

   }

});