Contacts names disappeared

[smileNBhappy]

I have the new iPhone 4 S 16GB, I'm new to apple but today some of the names of my contacts disappeared. The numbers were still there. Some were in favourites too. Please tell me if this is normal? and how to stop it happening again. I had synced to icloud but they were gone from there too!
Thanks!
p.s. Siri couldn't help!! He directed me to here!!

 

[iSaint]

Are they still in your Address Book on your computer? You can tell iTunes to overwrite all of your contacts on your iPhone one time.