Respringing after updating Mobile Substrate in Cydia bricked my phone?
I had the same exact problem today. I didn't want to update to iOS 7 either, but after so many hours on google, this seemed the only way to make my phone useful again. I followed this http://support.apple.com/kb/HT1808 and although it made me have to lose my familiarity with iOS 6 (RIP), my phone is useful again.