Folks,
I was so desperate to get this fixed and i found the link for the online windows phone support (
https://gethelp.live.com/en-us/Pages/wp8.aspx) and had a live chat with one of the executives.
Following are the steps to get this working
1. Remove the store tile from the start screen
2.Open internet explore and click on the "..." by the bottom right corner and navigate to settings
3.Click on "Delete History" and clear all the browsing history
4.On the same page, click on "Advanced Settings"
5."Accept All" Cookies from websites and apps
6.Once you are done with these settings , restart the phone and place the store tile again on the start screen.
I know u ll be frustrated even after the restarting the phone coz u wont be able to see the list of updates. But give it some time and it will start appearing again.
I did the same and in about one hour i got about 11 updates listed which was so surprising coz i am seeing them for the first time.
Hope this works for other 520 s as well
Thanks
Savio