Hello,
I purchased a new home (that was 95% completed when I bought it) that
was prewired for surround sound. I opened the plates where the
speakers are supposed to be attached on the walls, and found a (rather
low-quality) speaker wire there. There are four such plates. However,
the other end of the wire is not visible - no plates, exposed wires,
etc where I would expect to plug into my receiver.

The builder and electrician are completely unresponsive, so I can't
ask them for information. Is there any way to find out where the other
ends terminate?

Thanks for any help!