OK, first things first, if you go to the
Administration > Modules > Blocks > Manage Blocks
page, that will give you a list of all blocks and plugins active, or inactive, on your site.
Second, the plugins for v1.9 were not all updated for v2.x, this is because many of the maintainers did not update them. Many have been updated, and others, like the Book module, are now a part of Moodle core, so is no longer a separate plugin. Good luck.