Problem opening Apps on Iphone 4S

Last Sunday I downloaded Ringtone+++ and of course, I downloaded some ringtones using this app.  Following the instruction given, I transferred the ringtones I downloaded to my desktop and then, copied these ringtones to my iTunes library and thereafter, to my iPhone. Well, so far so good. Everything works as it says. I was a satisfied user. :) 

But then, a few hours later, none of the apps I downloaded can be opened! Not even one! I panicked. What's wrong with my phone?! It's just a month old, I can't be that unlucky one? 

I was playing a game I downloaded half an hour ago and was just texting using Whatsapp a few minutes ago, all of a sudden..everything was not working except those programmed apps. I was having doubts with the ringtones that I've downloaded to my phone. Was that the culprit? 

It happened when I was having dinner with my dad at Boston, De Garden. So, after dinner, we went straight to Kinta City, DIGI centre, where I've purchased the phone. Nobody can help...all the staffs there just tried to restart my phone a few times. One of them said the only way is to restore to factory setting. But I need to backup my phone with iTunes at home using my own PC. I was devastated. Is there nothing can be done other than restore to factory setting? He said all my apps will be gone. :(

Went home and backup my phone with iTunes. Did a search on google but maybe not thorough enough because I couldn't find anything helpful. In the end, I decided to press "Restore". While iTunes was downloading iOS 5, i found something on the web. Turn out some people do have this experience and someone suggested to download a new app to solve the problem. I find it a weird way... But I gave it a try and it really works! Luckily iTunes was still downloading the iOS 5 software and had not start resetting anything. I quickly unplug the USB cable. Whether it will continue with the restoration process when I plug in the cable next time, I'm not too sure. 

Everything seems ok these 2 days. New ringtone is working fine. Probably it's a problem with the sync process. I just hope that nothing will go wrong again. Fingers crossed!