i got a new j210i sonyericsson phone after one week of use when i fixed in my mtn sim it keeps telling me insert correct sim even after i inserted the fomer simcard the fault remains have any body gotten an idea of what could be done to restore the phone to its nomal state?

Sounds like a network lock to me but when I remember that it worked for a week I tend to think maybe the phone wasnt BRAND NEW when u bought it, sorry if that hurts to hear. U get guarantee from where u buy am?

The phone is locked to a particular network . Thats it.
Throw away the phone , _{Return it to where u bought it only if they will replace it for you}

i think the phone has been locked to one kind of sim, if that is the case, then I Know there is a password that unblocks it

What was the network you were using for that one week and is your mobile not working with MTN network alone or with all networks.... did you try checking with other SIM cards.. if the error remains for other networks also then your mobile must be locked to any particular network.... for your mobile to return to normal state you have to get it unlocked with any online unlocking service provider... when i had this issue with my mobile earlier I got unlocking codes from TheUnlockSpot.com.. tyr if you are interested...