Canon EF-S 18-135mm IS STM won't manual focus

I smacked the lens (see small chip out of the lens and cracked tab) which popped the manual focus ring and its outer brand containing ring out. I popped them back in and although the lens works fine in auto-focus mode it doesn't in manual. Since this is the STM version of this lens, the manual focus is not mechanically connected; it's focus-by-wire.
This is the kit lens that came with the Canon EOS T4i/650D and isn't worth much, at least not enough to send it out for repair. The store I bought it from said they'd sell me a used one for $100, but I don't even have that.
Out of all my four lenses, it's the one I use most often; it's the most flexible. Even if I would send it in for repair, I'd need a replacement for a while.
So, I want to try to repair it myself. The outer containing ring now easily pops off and on. I can't see where the focus ring connects to anything.
Can anyone help, please?