New Application cant be added to Ubuntu11.10

[Linux_Boy]

Hello friends !! . I had this strange problem . I had added new softwares through mu GUI application like add/remove softwares , or clicking in MoreApps>Application to be downloaded options . But while updating Ubuntu , i tick off which i thought irrelevant cost me dearly . Now i cant add new app to my Ubuntu 11.10 . When i click Application to be downloaded option it doesnt work , means it wont respond to my click. Now i figured out my GUI for add/remove too missing , so i need to explicitly type command apt-get ... Is there any thing that i cud go , to get back my GUI for new application installation .
Hope my problem is cleared , i''ll be happy to provide more info needed

Thanks with regards

[petern]

Have you tried doing an update again? If you can't get into a GUI for updating, then in a terminal you can use these 2 commands:

sudo apt-get update

sudo apt-get upgrade

I always update everything that needs to be, and never 'tick off' anything. I figure the people who maintain the packages know better than I do.