Cortana is nowhere to be found on my Nokia Lumia 520. I have downloaded 8.1. What gives? How could I get it? Can I reinstall the update somehow?
Try this:
1. Make sure that your mobile is upgraded to 8.1
2. BATTERY SAVER must be turned off.
3. Change your REGION & LANGUAGE along with SPEECH settings everything to UNITED STATES (ENGLISH).
4. RESTART your phone
Source
Please let me know if that works.