Wordpress Blocks Button missing

Hey guys,
while working on a new project, i realised that my Blocks are missing. What could i have done? The “Blocks” Button in the backend-navigation is missing from now. The last plugin i installed was ACF Pro, but i think the blocks where still there after the installation. The DB seems to work, the content from the already used Blocks is still there.

Do you have an Idea?

Thank you,

Mike