Have U ever had this? My phone was fine until tonight I notice no service, I go in it finds all 5 networks, I select o2 it registers but still no service, I am thinking phone might be blacklisted, it was bought of eBay brand new, how could I check?

Try another networks sim or call O2 on another phone and ask if it's blacklisted, they will be able to tell you if you quote the IMEI number.

You'll get the IMEI by typing *#06#

I got it working, I turned it off an on no good, pulled battery out no good, pulled sim card out and it worked again, Don't know what happened.

pulled battery out? u sure? the Lumia doesn't have a removable battery

Sorry should of said, it was a 710. But I have seen similar reports of this issue in the 710 and 800 over on the Nokia support boards,

Ahh right, got a little confused there lol