SOS cant access wordpress controll panel since installing study press plugin

Fatal error: Class 'AccessData' not found in /membri/radiographershideout/blog/wp-content/plugins/studypress/Study-Press.php on line 50

What do I do? It happens everytime I try to edit a post.

I cant log on to deactivate the plugin either.
Somebody help Pleeeaasee

You have to manually deactivate the plugin, just rename its directory.
However this is the Italian support forum, for support in English please use the international one.