You can not.. This is exactly why WP will never match Symbian. It had 'SUITE' which we could use to manage damn everything about the phone right from installing Apps to taking local back up to reinstalling firmware and so on. With WP you can only transfer photos, videos and music. Rest everything needs GPRD/3G/WiFi activated on phone and synchronized on Cloud/MS a/c. You can not take local back up of contacts/messages/calender events/notes/bookmarks/saved locations and just anything. If you lose screen/keyboard, you must get it repaired to get your data back. You can not just connect it to PC via usb and take backup, like you could in C7. This is one of the so many reasons why WP suck.
Still just one thing, if it can help. If you have created MS account when you purchased that phone and logged in to the account, phone automatically saves all contacts to MS a/c (Outlook or Hotmail or Live). Try to log in to that account from PC, if you remember the log in ID and password. You will get all your contacts back. Rest everything needs manual synchronization/backup. If you have set auto back up to off, you have lost those things.