My Software Center won't launch from the dock in Ubuntu 14.04/Gnome
 

Hey everyone:) 1st I tried to DL an upgrade of Vimeo fm Gmail, I searched the file manager to suggest open the link with "Ubuntu Software Center" and nothing appeared as a result.
And now..the Ubuntu Software Center won't even launch...
I tried to DL an app for an upcoming web project called jammr: http://jammr.net/download.html & the open/save box says open w Ub Soft Cent & USC isn't functioning- just opens grey window with no options, & closes immediately. Thanks for helping!

So I tried this & got this result::

sudo apt-get install jammr
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package jammr

Then I tried right clicking on the file I downloaded & saved to downloads dir from http://jammr.net/download.html, and selected gdeb pkg installer

and got: software index is broken mssg: This is a major failure of your software management system. Please check for broken packages with synaptic, check the file permissions and correctness of the file '/etc/apt/sources.list' and reload the software information with: 'sudo apt-get update' and 'sudo apt-get install -f'.

then i extracted the 3 dirs into my downloads, they are called 'DEBIAN' 'usr' & 'bin'
and I don't know what to do now. Thanks for helping!!!

So I tried this & got this result::

sudo apt-get install jammr
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package jammr

Then I tried right clicking on the file I downloaded & saved to downloads dir from http://jammr.net/download.html, and selected gdeb pkg installer

and got: software index is broken mssg: This is a major failure of your software management system. Please check for broken packages with synaptic, check the file permissions and correctness of the file '/etc/apt/sources.list' and reload the software information with: 'sudo apt-get update' and 'sudo apt-get install -f'.

then i extracted the 3 dirs into my downloads, they are called 'DEBIAN' 'usr' & 'bin'
and I don't know what to do now. Thanks for helping!!!

---------- Post added 09-25-14 at 02:57 PM ----------

So I tried this & got this result::

sudo apt-get install jammr
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package jammr

Then I tried right clicking on the file I downloaded & saved to downloads dir from http://jammr.net/download.html, and selected gdeb pkg installer

and got: software index is broken mssg: This is a major failure of your software management system. Please check for broken packages with synaptic, check the file permissions and correctness of the file '/etc/apt/sources.list' and reload the software information with: 'sudo apt-get update' and 'sudo apt-get install -f'.

then i extracted the 3 dirs into my downloads, they are called 'DEBIAN' 'usr' & 'bin'
and I don't know what to do now. Thanks for helping!!!

Post your /etc/apt/sources.list
You can also see if you can correct dependencies by:

Can please enlighten us on how you solved your problem si that someone doing a search will also be able to benefit from your experience.