How to trace/track my stolen Samsung Galaxy Ace 2
I strongly recommend you take a look at the lost-phone tag-wiki, which contains a lot of first-aid hints. As you write your SIM is still in the device, there's hope it's also still connected to your Google account and has a network connection -- so hurry up trying solutions like Plan B or Android Lost, which you can then push to your device via Google Play's website. Find more details in the linked tag-wiki, plus on the apps' page at Google Play.