You didn't answer "how did you install them?" however...
Can you confirm that you have a folder called theme/eguru and that it actually contains some files and sub-folders? You should at least be able to find lib.php, version.php, lang/.
The permissions (and/or ownership) of *all* the files and sub-folders need to be such that the web server can read them. 767 is odd but should work (755 is more likely but actually *more* restrictive). If you change anything remember to go to Site administration > Notifications to trigger the install.
If you still can't see them, eguru has a README.txt file which you should be able to see via a browser at...
http://your.site.com/moodle/theme/eguru/README.txt (substitute your site URL as required of course).
If that throws an error then check your web server's error log to see what's upsetting it.