Contax g1 photos completely out of focus!

Hi all,

I've been shooting with the my contax g1 with the 45mm lens. My last two rolls have been completely out of focus and I have no idea why.. this is the first time it's ever happened to me. And I'm not talking about just slight focusing inaccuracies but the entire picture is blurry, nothing is in focus. I always shoot in autofocus mode.

Is there anyway for me to check whether it's a problem with the back or with the lens? I only have 1 back so unforuantly i can't do a test with another

Thanks