Sony J7 SIM Lock and no IMEI

Hi,

I've got a weird problem.

I bought a Sony J7 about 2 years ago from Virgin.
Used it for about a year and then got Virgin to unlock it with a code
they sent me.

And was able to use any SIM in there ever since. Although cntinued to
use my Virgin SIM in the Virgin phone.

However, I tried to turn on the phone today and battery was totally
dead, So tried charging and light came on so thought it was charging,
but hours later it wasn't, so tried again and it did charge this time.

Anyway now everything on the phone seems to have reset itself, when the
phone was new it used to play a default tune when turned on which I
disabled, well that's back now. BUT now it also says SIM LOCK no matter
which SIM Card is put in there including a Virgin SIM Card. Any ideas
what can be done or what caused it?

I no longer have the unlocking code for the phone from over a year ago
because I didn't think I' ever need it again.

BTW I did *#06# and the IMEI code comes up as all zero's

is my phone totally screwed? It seems to work fine but only allow SOS
calls, can I fix it or reflash it? I think I have the serial cable for
it (not 100% sure though) But don't know what my IMEI number was before
not sure if I have the manuals to it anymore.