How can I get my phone contact back

If you are syncing them to iCloud, then give the following a try:

• Note: iCloud only archives 2-3 weeks of Contacts so any deletions before then will be lost.

1. Open iCloud.com in a browser, and then, log in.
2. Select Settings from the dropdown menu located beneath your username in the upper right corner.
3. In the next window, select Restore Contacts in the Advanced section located in the lower left window.
4. Select the date from those offered in the archive list.