I keep getting
W: Failed to fetch http://ppa.launchpad.net/gwibber-daily/ppa/ubuntu/dists/trusty/main/binary-i386/Packages 404 Not Found
when I do a apt-get update, also get failed to download repository information when i try software update.
How do i fix these?
It seems like you are using a non valid ppa
Please disable (by unchecking or removing) the gwibber ppa via Software & Updates (from Terminal: software-properties-gtk) in the Other Software tab
This AskUbuntu post explains removing PPA's as well.
Now open a Terminal and re-run
sudo apt update
or
sudo apt-get update
to update your package informations.
You should then be able to run
sudo apt upgrade
or
sudo apt-get upgrade
to upgrade your packages as well.
If you try to open up the ppa url in your browser you'll see as well that the entire url seems non existent.
I've checked the project url and it seems like precise is the last supported Ubuntu release for this ppa. I can only guess what you are using (trusty) as you haven't mentioned it in your post.
I had the same problem aswell, I solved it by running "software-properties-gtk", then go to "ubuntu software" tab and select another server from " download from" drop-down menu. In my case I chose Duke server in the US.
From a terminal use --remove flag to remove the PPA:-Similar to how the PPA was added
sudo add-apt-repository --remove ppa:whatever/ppa
FAs a safer alternative, you can install ppa-purge
sudo ppa-purge ppa:whatever/ppa
Alternatively hit Alt+F2 and run software-properties-gtk 
Click on Other Software tab, you'll see that each PPA have two lines here, one for the compiled packages and one for the source, Uncheck both lines to disable a PPA.Then update your sources list
sudo apt-get update
and try to upgrade again
sudo apt-get upgrade
