Cortana missing after Windows 8.1 update
Many users have tried Windows 8.1 Preview for Developers. Now their concern is Cortana app is not available after the update. There may be many possible reason. However the major reason is Cortana is not available for the countries other than United States. If you are not from United States then follow the below steps to get Cortana in your mobile.
1. Your phone should be updated with Windows 8.1
2. Your location is outside United States of America.
1. Go to Settings and open Region.
2. Select United States in Country/Region
3. Select Region Format as 'match phone language'.
4. Press back key and select Language (In Settings).
5. Choose English (United States).
6. You might have already chosen some language say English (United Kingdom). So English (United States) will be listed below English (United Kingdom). Long touch on English (United States) and drag it to the top. Now it is the first language of your phone. Now it should look like below image.
7. Now in Settings, open phone update and touch 'Check for updates'. A new update will appear which install Cortana app in your phone.