I fixed the problem as explained ahead.
Preface:
iPhone size: 16 GB
I noticed that after upgrading to the latest software update, I could not open any app at all. Syching or re-installing apps did not help at all.
I found that, the iphone was not synching completely as the size of data (music + apps + photos etc) in my iTunes software was more than my iPhone size - you can find this out by clicking on your iPhone after connecting to your computer.
How I fixed the issue:
1. Connect iPhone to computer. Chose option not to synch music.
2. Syched all the apps and other data such as photos
3. Removed the iPhone connection from the computer. Ensured that I can open the apps now - all done and
working fine
4. Re-connect the iPhone to the computer. Manually select the music albums songs etc. Be careful not to exceed the limit of your iPhone storage.
I hope it helps.
Thanks.
Regards
Prasad