The Canon EF 35mm f/2 seems to be notorious for having its focus lock unexpectedly. It happened to me on my used 35mm f/2 (about 6 months after it was dropped) and it happened to my friend on his new 35 f/2 after about 6 months. His first time, it was still uner warranty, so he got it repaired for free, but the symptoms were exactly the same as mine: No auto focus, ring locked in manual. It happened to him again less than a year after having it fixed!!! After looking at the lens, I thought it had to be the same problem again. Yep, it was. A small screw and bracket that get slightly out of line and cause the barrel to get stuck. Easy to fix, but you have to use the right screw drivers or you might strip the screws, and you have to be good at soldering! Enjoy! (sorry the pictures are bad, I didn't try very hard to get good ones).

By the way, if you have this problem on your Canon EF 35mm f/2, I'm willing to fix it for a small fee (less than the repair company) and much faster. My friend got his back in only two days.

The lens before fixing it.

The top part has been removed, although it didn't have to be.

Taking off the snap-in cover.

Removed four screws holding the mount to the body and two screws holding the contacts to the mount. Also desoldered two of the thin wire assemblies (leave the one with the most connections in place -- you only need to desolder two!)

There's the problem!! Loosened the screw, wiggled the barrel a bit. Focus ring loosened up immediately. Retightened screw and made sure the focus ring was still loose.

The tools and the process.

Wait... that's not the 35mm lens! That's because the picture was taken with the 35mm!

Test near focus.

Test far focus.
Awesome!!