Help Xperia LT28at unknown baseband and blank imei

Need help for my Xperia LT28at no baseband and Blank imei.... may cousin gave this phone to me...when i try to insert simcard it prompt no sim recognize...when i try to check the IMEI it was blank and i check about device unknown baseband...itry to flash the unit with different FTF file LT28at stockrom and itry to LT28i and last itry it with LT28h jelly bean 4.1.2 but nothing happens.... is there any other solution to fix unknown baseband and Blank IMEI... hoping fof your help and advice