Contacts are neither stored locally on an iPhone nor in SIM.

Contacts are neither stored locally on an iPhone nor in SIM. They are synced to an email account that you had Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other

1. How many Contacts account (email client server) you have / had? If you have removed any add it back.
2. What is your default Contacts Account? That is where contacts are added now. (Read more below...)
3. Which email account you are using to store Contacts? It could be more than one for display, edit etc. for contacts are only added to Default account.

• See the GIF below for Contacts and Default Account

• Learn how to add an email account and make it default (Watch the GIF)
• This example is for Gmail but the process remains same for all Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other