Here are a few options you can try:
Your iPhone backups are located at: c:\Documents and Settings\Application Data\Apple Computer\MobileSync\Backup
After you have your iPhone connected to your computer, locate the iPhone in the “Devices” column at the left of the iTunes application window.
Right-click on the iPhone icon in the “Devices” column and select “Restore From Backup.” Select one of the backup versions from the drop-down menu and click the “Restore” button.
Or you could do a system restore by typing in restore in the search box at the start menu. This will not erase any personal items such as music or pictures.
Or…settings > Mail, Contacts, Calendars > Import SIM contacts.
Or…you should always keep a list of your contacts saved to a usb, on your computer or in a paper notebook for easy access and backup purposes. There’s this free program called contact keeper which lets you organize names and addresses.