how to restore my contacts??

That depends on what email account your contacts are synced with. If all of your contacts sync with iCloud, see→iCloud: Restore contacts, calendars, and more in iCloud Settings. If some or all of them sync with other email accounts, such as MS Exchange, Outlook, AOL, Yahoo or any other email providers, check the site for the provider.

You can also verify that you are viewing all contact groups. Open the Contacts app; if you see Groups in the upper left corner tap on it and make sure all groups are checked.