Save button not working in articles - Joomla! Forum - community, help and support

hi !

am unble edit , save changes in article kindly & error seeing in chrome console..


uncaught typeerror: cannot call method 'isvalid' of undefined index.php:293
joomla.submitbutton index.php:293
onclick index.php:237

had posted ticket in hosting service provider , got following reply

since issue not related server misconfiguration, ask site developer revert recent code changes, uninstall added modules / plugins.

i tried backup site did not me dont have oldest backup ..

i have (in last 2 days?) found cannot save articles, categories (new) etc, using j3.3.6, trying on more 1 pc, linux mint or w7, far know, no significant changes, new extensions etc.
this on new host (since 1 week +); site copied complete host , old copy ok, running newer version of php ie 5.4.32 versus 5.4.28 of new host.
i tried a) upgrading new host vers 5.5.. changed hathor admin pwd, c) uninstalled installed extension, of several days ago; still no result on clicking save, save , close, cancel etc although button changes slighly; expect see waiting mysite?
any answers please? thanks. trevor