How do you check for damaged wire in walls? HELP

I have lost the same channel on an amplfier twice now. It runs to a rear surround that was installed last year by me. Pulling the cable was difficult (hard to pull) I was afraid that I may have damaged the wire. I hooked it up and it worked great. I have done a ohm resistance test that reads .008 on both rear surrounds. I am not sure if this test will tell me if the wire is damaged. If anyone has any ideas as to any other tests I can do before I attempt to run anther wire it would be much appreciated
I'm not sure what you mean you have "lost" the same channel on the amp? Blown fuse? Sounds cuts out? I'm also not sure what you mean resistance test, did you measure each strand, or short the amp or speaker ends and test the leads on the other side?

If you "damaged" the wire, it could either be a short (the + and - are connected together at some point in the wall) or a break (either the + or - is cut). The problem is that its likely that its an intermittent short or open circuit. I'd try the following:

1. Disconnect + and - from amp and speaker end, make sure + and - are not touching on either end. Measure the resistance between + and - on both sides. In both cases, it should be infinite--usually a 1 on any setting of your ohm meter. If its not infinite, it means the two strands touch at some point in the wall, you can stop there and think about running new wire.

2. If not, twist together the + and - on the speaker end, leaving the two strands apart and disconnected on the amp end. Measure the resistance between the two leads on the amp end. It should be close to 0--i.e., you should see just the internal resistance of the wire. If its still infinite, it means that there is a cut in one of the two strands.

Those are simple tests, but may not tell you if there is an intermittent short in the wire--in other words, if there is cut so that the two wires are close enough that applying a sufficient voltage across them causes an arc across the gap. If that were the case, you might, in fact, blow a fuse on one side of your amp. If that has been what's happening, you might try:

3. Reversing the channels on the amp--run the left RCA input into the right channel, and wire the left surround to the right speaker out. If you were blowing the right amp channel, and now you are blowing the left amp channel (now connected to the right speaker wiring and right speaker), its probably a problem with the right speaker wiring or right speaker. If you were blowing the right channel of the amp and continue to blow the right channel of the amp, its an amp problem.

4. If the problem reversed sides in (3), try switching the surround speakers so the left speaker is on the right side and vice versa. If the problem stays in the same place, its the wiring. If the problem switches sides again, its probably the speaker.

Long answer. But its all I can think of to do.
It would be easy to check the wire for a short. Take your meter and set it for continuity and touch the leads to the positive and negative. It should beep if there's a short. To check for a broken wire, twist one end of the wire together and check for continuity again. If the meter doesn't beep the wire is broken.