Contacts app on iPhone5 stuck on "groups" page.

Running current iOS (8.2) on an original iPhone 5.

Recently, and I don't know what started it, I went into the "groups" menu on my iPhone, where you can select what groups are synced on the phone. When I had reviewed them, I clicked "done", assuming that would take me back to my database of contacts. The program quit. Every time I launch, it launches to the Groups page, and quits when I click "done". There's no other option on the page.

I've tried selecting/unselecting different groups. No change. I've turned the phone on and off. No change. I've tried the reset with the home & power button. No change. As a core Apple application, I can't get rid of the app and reload it. How do I progress?

For the record, my contacts list in the phone app is still there.

Thanks for any suggestions!

Antony