Help Sim card Problem

[naashi]

Hey guys I m using xperia neo v. it was running Android OS, v2.3.4 (Gingerbread). my friend took it and just installed v4.0.
Now I am in big trouble, Because My sim card is not working any more and v4.0 is just bad. I want to come back on older version. plz help me out to do that.
I am waiting

 

[maximusx8]

id suggest goin to ur nearest sony service center and asking them to restore it to 2.3 again.. thats the best u can do... but its ur choice.. best of luck..