ipsec shared missing

For some reason, my ipod isn't connecting Facebook or youtube or the app store. It is only letting my use google and safari and i can'tpurchase any apps from my ipod. Every single time I check settings, it says that the VPN is off. when i try and turn it on, it says: The IPSec Shared Secret is missing. Verify your settings and try reconnecting. What do I do to get my internet and my app store back?!