blocks are disappeared

Hello! Ive been customizing the blocks which my homepage will suppose to contain and after saving the changes, when i go back to block option again, i see nothing but the crumbs and the title "Block". I don't know what to do and of course i do not want to repeat again the installation of opigno since i established the contents. I thought flushing the caches would help me but the problem stays there. Also, other menus were affected such as courses, user menu, training catalogue, when i go to user's profile, it displays nothing. Even clicking to a course at homebox, i cannot see its contets. What should i do? PLease help me. Thanks in advance.