boot - Plymouth Error - booting and shutdown error

I have messed up my plymouth settings in Ubuntu 16.04 when trying to install new themes. And now my system won't shutdown and freezes.
At boot systemd generates kots of error messages. But the system starts up and works correctly(except shutting down).

  plymouth-start.service: Start request repeat
  May 24 11:06:48 atla-pc systemd[1]: Failed to start Show Plymouth Boot Screen.
  May 24 11:06:48 atla-pc systemd[1]: friendly-recovery.service: Start request rep
  May 24 11:06:48 atla-pc systemd[1]: Failed to start Recovery mode menu.

  May 24 11:06:48 atla-pc systemd[1]: systemd-fsck-root.service: Start request rep
  May 24 11:06:48 atla-pc systemd[1]: Failed to start File System Check on Root De
  May 24 11:06:48 atla-pc systemd[1]: systemd-hwdb-update.service: Start request r
  May 24 11:06:48 atla-pc systemd[1]: Failed to start Rebuild Hardware Database.
  May 24 11:06:48 atla-pc systemd[1]: sys-kernel-config.mount: Start request repea
  May 24 11:06:48 atla-pc systemd[1]: Failed to mount Configuration File System.
  May 24 11:06:48 atla-pc systemd[1]: systemd-binfmt.service: Start request repeat
  May 24 11:06:48 atla-pc systemd[1]: Failed to start Set Up Additional Binary For
  May 24 11:06:48 atla-pc systemd[1]: systemd-ask-password-plymouth.path: Start re
  May 24 11:06:48 atla-pc systemd[1]: Failed to start Forward Password Requests to

  May 24 11:06:48 atla-pc systemd[1]: Started Braille Device Support.
  May 24 11:06:48 atla-pc systemd[1]: sys-kernel-config.mount: Start request repea
  May 24 11:06:48 atla-pc systemd[1]: Failed to mount Configuration File  System.
  May 24 11:06:48 atla-pc systemd[1]: plymouth-start.service: Start  request repeat
  May 24 11:06:48 atla-pc systemd[1]: Failed to start Show Plymouth Boot Screen.
  May 24 11:06:48 atla-pc systemd[1]: systemd-ask-password-plymouth.path: Start re
  May 24 11:06:48 atla-pc systemd[1]: Failed to start Forward Password Requests to
  .......

Can anyone help me to reset plymouth?