Whenever I have such an error, I first check if I don't have a more recent version of the library.
ie the .so.1, .so.2, etc file.
To do this, you can try something like:
Or, leave off the '0' at the end.
Secondly, the library seems to be part of the gtk2 package. So you may want to check if it's installed:
rpm -q gtk2
or something like that (if your Linux distro is rpm based).
Or, you can try searching the package that contains this library file.
To accomplish this, go to a site like http://rpmfind.net
(again, if your distro supports RPMs) and search
for the lib file there. It will show you the package that contains the file and you can download it from there.
Make sure to download the appropriate version (for your distro/platform).