Why has my iphone 4s switched from displaying names to numbers?

[iMore Question]

As of this morning when I receive a text message from people who are loaded in my contacts list my phone has suddenly switched from displaying their names to just their number....I am unaware of having changed any settings. Can you help please?

 

[Rob Phillips]

Welcome to iMore! Are you still able to see them in Contacts? Also try this:
1. Open Contacts
2. Tap on Groups
3. Uncheck all groups, then re-check them
4. Perform a hard reset. To reset your device, hold both the power button and home button down until you see the Apple boot logo.