With the advanced tools and communication system we currently have in this modern era, nothing seems difficult or impossible.
Track a location with GPS & Google Earth:
Tracking location is considered illegal and you might be sentenced to imprisoned according per IT ACT. However, one can try Google Earth for GPS to track down the last location if the culprit or someone whom you spying had distroyed the Subscriber Identidy Module (SIM).
File the First Information Report to your neariest Police Station:
This is a legal process. You must report or take actions or file an FIR only after Twenty Four Hours. Police can easily track down the last location in seconds. Provide them the IMEI no. or Mobile Phone IMEI no. which you want to track. In case, if possible, give them the Mobile IMEI no. Even if they destroy the SIM Card, with the IMEI no of mobile they can hunt down no matter anywhere they put off in earth unless the phone isn't switched off.
Post a Notice or Wanted or Missing notice with Photo of the person:
This is highly recommended if you want the person at any cost. You can book your Ad Space in Newspaper and post a lost, missing information with high resolution image in clear format. This may cost you some charges. Anyhow, include your phone no and address in the Ad information, so when if people notice the person, they'll inform you.
Last but not least, the last option is recommended if they had destroyed both the SIM and phone.
Hackers never learns but always wins!