i have had my iphone jailbroken with blackra1n for a few weeks now and all of a sudden my internet tethering doesnt work now...the the option in settings to tether is still there but it just doesnt do it, i can turn it on/off but it doesnt actually connect? what gives?
any ideas on how to fix this?

not sure if this happened after or before the latest cydia update as i havent used internet tethering for a couple of weeks, but i know it was working after jailbreaking, and worked for a couple of weeks, i know that for sure.
it may or may not have happened after i had the visual voicemail activated with vodafone the other day (as i had the iphone replaced a month ago), part of the procedure was to reset the network settings.
not sure when i lost internet tethering, but how do i get it back?
i live in australia and am with vodafone so i have internet tethering officially on the phone. this same thing happened to my last iphone 3gs, this one i have now is a replacement.

ive now put on MyWi and tethering works fine through that, but i shouldnt have to use MyWi why doesnt the normal tethering option work anymore?

any assistance would be greatly appreciated!!!