When you say you "uninstalled TinyMCE" does that mean you deleted the tinyMCE folder from your Moodle directory tree? Or that you went into the Manage Editors page and clicked "uninstall"? It seems to have gone altogether in either case then?
If deleteted from the tree, then all you need do is to extract the directory from the downloaded file and copy it to the text editors directory you deleted it from. Reenter your Moodle and it should appear in the Notifications page as being an update.
Otherwise, chances are that the TinyMCE editor has been deleted from the Moodle Database but remains in the Moodle directory tree If you have access to the database, then you can go to the database.mdl_config table and in the field "texteditors" add the tinymce to the list of atto,textarea. It should then reappear in your Manage Editors page. Just swap them about, placing TinyMCE first.