If this is not a very old case and your ex-bf was using his phone within last one year, then it would be a good news. Telecom companies are requried by law to keep all the details with them for a year. So if you are able to provide phone number of your ex-bf to the police then they can trace the details within one week and detain the accused immediately.
In my view, yours is a case of Cheating S.417 IPC & Criminal Breach of Trust S.406 IPC which is cognizable and non-bailable offence. Hence once the case is filed under these sections, the person would be bound to return your money.
For the purpose of filing an FIR, you can seek help from any of your relative or friend in India. They can go to the police station in with a written complaint and they would register the FIR instantly. If anyone refuses to register the complaint, the ask your friend/relative to call 100 seek their assistance to register the FIR. If still you cannot get the FIR registered, then you can approach any local NGO or may be Indian Against Corruption volunteer to get help. Else you can make call to any news channel to take their help and expose the police. There are other ways also to get the FIr registered like sending letter to Comissioner of Police, Chief Minister of State etc etc etc.
Once the FIR is registered, you would be required to visit India once or may be twice. You can engage a lawyer in India who would convince the Judge that as you live in USA so he/she should ensure that your statement is registered on the specific date and no delay or adjournment is allowed. I think it would be easy.
Additionally, I strongly feel that once your ex-bf is arrested, he would immediately get ready to compromise with you and return the money. That would be more better to settle the case of of court. In case of S.406 IPC / S.417 IPC, generally people prefer out of court settlement and get their due money. All the best!
If you need any further assistance you may reply..