Can I find my stolen iPhone if someone reset it and uses different AppleID?
Just be sure to switch on Find My iPhone in Settings > iCloud
then not only can it not be reset by anyone without your AppleID &amp; password, but can be   


Pinged to play a sound [if you just lost it in the house],  
remotely put into Lost Mode [which will enable you to put a message on the lock screen, with another phone number to be contacted at, if someone finds it],  
or in extreme circumstances, remotely wiped [though this will itself then disable Find my iPhone].


All this can be done from another iPhone or on the iCloud web site at https://www.icloud.com/#find

See this question &amp; answer to see just how impossible it is for a thief to be able to reset it once you've secured it - How can I bypass Activation Lock?