The LCD has probably gone out. A new lcd and be ordered on ebay for about $30. Or your local repair shop should be able to repair it for around $60 - $70
it might be your headphone that is broken and yes it probably can. just bring it down to your networks local store and they will try to solve the problem straight away!
Go here: http://www.sonyericsson.com/cws/support/phones?lc=en&cc=gb
Then under Quick Links, setup Mobile Internet, MMS, and Email. Everything should work afterward!
It does sound like the sim reader might be malfunctioning or the sim card could be worn.
in this case i would recommend you simply try another sim card with the same network before assuming its the sim card reader.
I hope this helps :)
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