Samsung Galaxy S II :: Mobile Data Connection Isn't Working

Yesterday i used the the mobile data connection just as normal. I downloaded from the store and everything. Then i was back in wlan. I tried Fring. I wanted to try Fring also on 3G or Edge or HDSPA or whatever comes out from my handy and goes into the air ^^ I don't know anymore.So I turned off my wlan and was down. No internet anymore and even there was no icon in the toolbar.

I turned my phone on and off, unistalled every app i installed since the last time it worked, which was just an hour before that.
The things i installed were: A brightness widget (appears under volume controll if you press the volume buttons. I forgot the name.) and "Quicksettings", which leeded to uninstalling the first mentioned unit.After that didn't help either, i changed the card in my phone with another from the same provider. It didn't work. In the same move i put my card to another smartphone and got a connection.Conclusion: Either my phone is misconfigured (which i hope for) or it's broken (which would suck but i have warrenty left).

I even tried to let my provider send me the right connection data and saved them. Nothing...I know there is the way of getting back to factory settings, but i only want to try that if i'm running out of possibilities. And of course i don't want to lose my app data. my phone is not rooted now and i know i have to, to save my app data and apps (which sucks. 1-0 for the iPhone). I you have only ideas that could be done by rooting my phone i would do so, but i would rather avoid that because of the 'maybe warranty loose'.