Contacts disappeared overnight from my iPhone overnight

On the 31st July I went to use my phone and my contacts list had disappeared overnight. All my recent calls show phone numbers without names. I did not have icloud back up and 7 years of contacts have disappeared. The contacts from my first I phone appear to have remained on the phone but that is all. There is 16Mb of contact data still on the phone but I'm not sure what it is or how to get it off. It should be more than the 36 contacts I can see!

[Re-Titled by Moderator]

Original Title: Lost Contacts