You should have reported the original SIM as lost then O2 would have sent you a new one with the same number
Guide: Lost or Stolen O2 Device? - How to Report it
Best bet now is to ring O2 on 4445 and see if it is possible to migrate your old number across
Guide: How to find help & contact O2
This is not O2 and we are all customers here similar to yourself and cannot answer account type queries.
