You can restore lost contacts on your iPhone in a few ways.Crystal Cox/Business Insider

You can restore lost contacts on an iPhone from a recent backup using the iCloud website.
Your existing local contacts on your iPhone will be backed up and replaced with the ones from iCloud.
To restore contacts without losing data, merge your iCloud contacts with the ones on your phone.
If your iPhone is your central communication hub, responsible for voice calls, text messages, email, as well as all sorts of other messaging apps as well, then your contacts are no doubt critical. 
Whether you accidentally delete some contacts or lose your entire address book through a catastrophic mishap, all is not lost. You can easily tap into iCloud and restore your contacts from a recent iPhone backup.
How to restore lost iPhone contacts from iCloud1. Open iCloud.com in a web browser and sign into your account.
2. Click on the profile picture icon in the top right corner of the screen and select iCloud Settings.
Click "iCloud Settings" on the website.Stefan Ionescu/Insider
3. Select the Data Recovery tab in the top menu.
Go to the "Data Recovery" tab.Stefan Ionescu/Insider
4. Click on the Restore contacts card.
Click "Restore contacts."Stefan Ionescu/Insider
5. In the pop-up window, find a recent backup that you want to restore and click the Restore button next to it.
If there’s more than one backup, choose the one you want to restore.Stefan Ionescu/Insider
6. In the next pop-up, confirm your decision by clicking Restore again.
Your selected backup will replace all the contacts on your iPhone — it’s not possible to selectively restore just a selection of contacts from iCloud to your device. Any existing contacts on your iPhone will be backed up in a new backup archive to iCloud, though, making it possible to restore them again if you need to.
Important: To restore your contacts, your iPhone needs to be configured to back up regularly to iCloud.
You should also wait for the restore to complete on your iPhone before you make any additional changes to your contacts. If you add, remove, or edit any contacts while the restore is taking place, those changes could be overwritten or replaced by the restore process.
How to restore contacts without losing data after the latest backupIf you want to keep both your existing contacts and restore the ones from a recent backup, you can simply merge the contacts on iCloud with the one on your iPhone.
1. Open the Settings app.
2. Tap your name at the top of the Settings screen to go to the Apple ID page.
Tap your name to go to the AppleID page.Stefan Ionescu/Insider
3. Tap iCloud.
4. In the Apps Using iCloud section, tap the toggle next to Contacts to turn it on – it will go from having a gray background to a green one. If it is already on, toggle it off – make sure you select Keep on My iPhone in the pop-up so your contacts are not erased – and then toggle on again.
Tap the toggle next to Contacts.Stefan Ionescu/Insider
Quick tip: If you don’t see the Contacts toggle right away, tap Show All to go to the Apps Using iCloud screen. You should be able to find it there.
Tap "Show All."Stefan Ionescu/Insider
5. In the pop-up, tap Merge to sync the contacts on iCloud with the ones on your iPhone.
Once the merge is complete, you should see the contact from iCloud appear in your contacts list on your iPhone, along with your existing contacts.
Read the original article on Business Insider
Business Insider
https://www.businessinsider.com/guides/tech/lost-contacts-on-iphone