No pressure at only one location

I have noticed the water in the door on my refrigerator running slow and it isn't making much ice either. started checking things, wasn't the filter, unhooked the water line going into the frige and put it in a bucket and found that water was just trickling out. blew out the hose with no change so my next step was to replace the valve in the wall. well that didn't change anything either. obviously there must be some sort of blockage or leak in the pipe leading to it, though my water bill shows no signs of extra use and the faucet in the sink runs fine and so does the washer hookup on the other side of the wall. I would really appreciate any input as to what could be the problem and how I could go about fixing it, thank you in advance.

Post a picture of the line and where it connects to the valve.

If you are referring to the line on the house side of the valve its inside of the wall and all I can see is a bit of pipe and the 90 deg elbow that turns up and the valve screws directly into that.

What type of pipe in the wall? Copper, steel or pex?

Copper, runs into a brass 90. About 8 feet down the wall on the other side is the washer hookup so im guessing it ties into that, no problem with the washer though. House was built in 1982 I have never heard of a blockage in a fresh water line before.