can I retrieve deleted contacts

If you have a back up that has the contacts, you can restore the back up to your phone. However, any information you've added to the phone since the back up was done will be deleted.

What to do you sync your contacts to, iCloud? Yahoo? Gmail? Something else? Have you checked that account from another device?

As I know, If the contacts deleted, it still store in iPhone, if it isn't overwritten by other data, you can recover the deleted iPhone contacts, you can search in google to find a tool to help you, I holp you make a backup with iTunes or iCloud, then follow this from Apple:

http://support.apple.com/kb/ht1766

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<Edited by Host>