not able to use svn command from terminal in Mac OS 10.8

It looks like your local copy of "svn" (installed in /usr/local/bin) is dependent on a library that doesn't exist in /opt/local/lib anymore (which might have gone away when you uninstalled and re-installed the latest version of your svn client).

On my own machine, "svn" was installed into the "/usr/bin" directory via the Xcode command line tools, which you can download from Apple directly here (look at the "Looking for additional developer tools?" link) or you can install the command line tools directly from Xcode preferences (look in the "Downloads" tab, there will be a "Components" section). Once you install the command line tools, you can them "rm" the copy of svn that's in "/usr/local/bin".