checking updates in Terminal error

[f23948]

when i check for updates it gives me error

Code:

___@___-HP-Compaq-dc7800-Small-Form-Factor:~$ sudo apt-get update
[sudo] password for ___:
Hit:1 http://repo.linuxliteos.com/linuxlite citrine InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial InRelease                     
Get:3 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]     
Get:4 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]   
Hit:5 http://archive.canonical.com xenial InRelease                           
Hit:6 http://ppa.launchpad.net/nemh/systemback/ubuntu xenial InRelease         
Hit:7 http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu xenial InRelease
Get:8 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB] 
Ign:9 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial InRelease       
Hit:10 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu xenial InRelease       
Ign:11 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial Release
Ign:12 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en
Ign:12 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en
Ign:12 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en
Ign:12 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en
Ign:12 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main i386 Packages
Ign:13 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en
Err:12 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main i386 Packages
  404  Not Found
Ign:13 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main all Packages
Ign:14 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en_US
Ign:15 http://ppa.launchpad.net/richardgv/compton/ubuntu xenial/main Translation-en
Fetched 306 kB in 5s (60.6 kB/s)
Reading package lists... Done
W: The repository 'http://ppa.launchpad.net/richardgv/compton/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://ppa.launchpad.net/richardgv/compton/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
___@___-HP-Compaq-dc7800-Small-Form-Factor:~$

any suggestions?