Wiping cache should be harmless - I do this regularly. I know you can't answer this directly (unless you register), but are you sure you didn't wipe anything else?
I'm guessing from the phrasing that the phone is rooted with a custom recovery. If so you should have a number of options. But we'll need to know a bit more to point you to the right answer. If you could post again with more information about your phone (which model, or which country and which network) and everything you can remember about what you did and what software it was running, that will help us get you the best answer. You could post again here, or you could register so that you can post in the main forum, which would let us discuss things more easily.
Of course if you are sure that all of your important data are OK you could just try a factory reset. As long as you did not wipe system as well as cache that should get the phone working again, but that will erase all of your apps and their data, so I'd prefer to avoid this if I could. And if the reason it won't boot is because you erased something else that you shouldn't have, then a factory reset won't help. If you actually are rooted with a custom recovery, I'd take a backup from recovery before doing a reset, since that way you have a copy of your data.
Good luck!