YUM/RPM do not work at all in Centos 6.3 x64 bit edition

Ok, I messed up my yum/rpm utilities in Centos. when i try running either or, with any and all files or options, i receive the following errors every time:

yum:
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

libdb-4.7.so: cannot open shared object file: No such file or directory

Please install a package which provides this module, or
verify that the module is installed correctly.

It's possible that the above module doesn't match the
current version of Python, which is:
2.6.6 (r266:84292, Sep 11 2012, 08:34:23)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)]

If you cannot solve this problem yourself, please go to
the yum faq at:
http://yum.baseurl.org/wiki/Faq


and with rpm:
rpm: error while loading shared libraries: libdb-4.7.so: cannot open shared object file: No such file or directory


this all started when i, perhaps foolishly, issued the following command:
rpm -e db4-4.7.25-17.el6.x86_64 --nodeps

which i did while i was trying to fix a dependency problem i was having with installing other packages.

what to do? so far i tried copying the file stated as missing into the directories /lib and /usr/lib. i got the file from online sourceforge location. not sure what else to try doing.

thanks everyone.