Dropping, bumping, knocking it about—all are possible causes of shock damage. The symptoms can vary greatly, and not all of them are curable while you're out and about. However, there are sometimes things you can do.
If you have a lens error caused by some lens barrel pins gotten off track, then your likely fix involves a little more prodding. Try gently tapping the lens barrel while holding it at a variety of angles to try and bump them back into place. Check out the same lens error article as for sand damage for more details.
You might be able to work around the damage in the meantime. For instance, with a cracked or scratched lens, you can learn how to take good pictures despite the flaws - think damage reduction.
Otherwise... well. You've probably broken your camera pretty thoroughly, and there's not much you can do while you're traveling. You could purchase a cheap point & shoot for under a hundred dollars as a stand-in until you get home.
For bringing it back, make sure that you store all the parts in a padded, dry bag, preferably a carry on, as a damaged camera is even more vulnerable to further damage. Once home, you can either get your camera repaired, either through the warranty or as a DIY job, or if all else fails, spend some time researching your options for a new camera and purchase.