NextCloud is updated to version 14, tonnes of apps now but the upgrade blew up and I had to do a mostly fresh install.  If you used your system login here, that should work but initially you won’t see your files.  If you created a login then you will need to re-register.  Once you have logged in let me know and I’ll attempt to add your existing files to the database.  If you re-register be sure the login you use is the same as your old login.