Losing you cell phone is bad but what else you lose and which is more valuable than your cell phone is your data in your cell phone. Most important is your contacts. Many times I come across mails that says, I lost my cell and hence I need all your contact phone numbers. I find it very funny. At least with those you have Nokia phones. Specially Nokia smart phones.
There are various ways by which you can claim your phone book. But many cell phone users are not aware or lazy to keep a backup of phone data. I am listing few here. You can add your one as well.
Install OVI/Nokia PC Suit and Sync your contacts and calendar with Microsoft Outlook. Sync it frequently. But make sure that you keep your Microsoft Outlook Personal folder in which you have your address book at a location other than C Drive so that you do not lose your data when you format your PC.
Take Backup of your phone using OVI/Nokia PC Suit and restore it whenever required. Again, keep this backup on any drive other than C Drive.
Use www.ovi.com and your cell phone to store your contacts online using Sync tool in your cell phone. So even if you lose your data stored on your PC because of formatting, still you can reclaim your contacts data.
If you use 2 Nokia Cell Phones, use Switch functionality in your Nokia phone to sync data between both the phones.
I hope this helps you to reclaim your contacts. I wish that you do not lose your phone or your data even if you use reset to factory settings.
Let me know if this is useful. If you know any other method, please feel free to share it by commenting on this post.