/etc/yum you deleted all configuration to yum, no wonder it doesn't work now. Luckily, the contents of that directory are part of the yum package (at least on Fedora, a close relative), so just reinstalling yum using rpm directly should fix this. Find out the exact version you have installed, and then do something like
rpm -Uhv --replacepkgs http://mirror.centos.org/centos-5/5/os/x86_64/CentOS/yum-3.2.22-40.el5.centos.noarch.rpm (this is for CentOS 5, look around in that site for your version if not 5). If this doesn't work, rummage around for updates in directories like
http://mirror.centos.org/centos-5/5/updates/x86_64/RPMS/ for a file called similar to the above). Once that worked, do a
yum update --skip-broken for good luck. A victory dance afterwards is optional. Going to the next wall and hitting the head hard isn't: It might help to remember that Linux does exactly as told, even if it doesn't make any sense. You are supposed to provide said sense.
Do not use
--force on RPM, it tells it to go ahead even if dependecies aren't available, the result is a inconsistent system (that is very unlikely to work right). Don't ask when it should be used, it is a last-resort fallback for desperate situations. Like doing surgery with a swiss-army knife in the park.