Where exactly is the ABS valve

Fluid is not coming to 1 wheel only after changing rotor and pads. I had a little ordeal w/the caliper for awhile, where I thought the piston was not all the way down, and it probably was fine. But, to get it out and change the boot and put it back in, I had to pump the piston out using the pump the brake w/caliper attached method. Now I can't get any fluid to that one and the master cylinder is full.

Mechanic at Brakes For Less shop said the ABS pump is bad then, and you know that can be an expensive fix. I read or saw I think on your page or somewhere that some cars have a valve that may just have tripped to prevent fluid lose and just needs to be opened back.

BTW, I can't tell a lot from that pic. Which number on there is the valve? When I find it, is it easy to open?

Thanks

BTW, Brakes for Less didn't actually look at it. They were nice enough to give me info. Over the phone after I described the situation them. Can I not make sure first that the pump is bad by some other means of elimination? Or does it sound like it really is bad?
This is going to end up like at least $275($100 somebody's used junk yard part + 175 labor to install) + taxes for just coming from needing to change rotor and pad. Need to avoid that.