How to reformat k618i sony ericsson? - Sony Ericsson K750i Cellular Phone

Download the manual and search for it.
http://www.retrevo.com/pdf/23436dj291/9/More+features#q=Sony+Ericsson+K618i

you imei has been blocked by service center. go to sony erricson service center and activate it. must take mobile box and guarantee card with you. and also invoice if u have.

for details visit this Mobile Solutions

That means that the speaker in your phone is broken. This is very common in Sony Ericsson phones for some reason. You can buy speakers on-line or at some specialty stores for phones. However if you do buy one on-line the seller will expect you to know how to install it and it may be more of a risk to try to dissect your $200 rather than to just bring it into a radio shack or other kind of phone store

Call 3 Care and ask them to unlock it, they might do it for free. I've unlocked 2 phones with them free of charge like that. If they won't do it free, read here how to unlock your phone.

may know whats the problem

No There is no such code.

try unlock codes from http://www.mobile-unlocker.com/

take out your battery, sim and memory stick.. then turn it off for 5 minutes, then turn in on without inserting the memory stick. after that try sending sms again, if it delivered,then try it with memory stick. if u can send sms,then its ok..but if cant then your memory sticks got a problem.my suggestion is to format the memory stick..

chang ur screen mn

Hello
You could try doing a master reset but you will lose all data / contacts /pictures/ on your phone
Steps to do a master reset
Settings/general/master reset/reset all/continue
Phone will restart