Imagine you wake up tomorrow with a new family in a new country…what happens next?

i will be very surprised

Well Obviously I would be very shocked

Explanation:

Assuming that this "New Family" knows you as their son/daughter, I would play along at first. Get my bearings, find out which country I am in, who these people actually are, what year it is, (If you have woken up in another country anything could happen at that point) And most importantly... How to get home. Now assuming this country also speaks your native language (Or if you have picked up a new language over night) then blending in and understanding where and when you are will be much easier. So the first thing that you do when you wake up, brush your teeth, eat some breakfast, all that morning stuff. Now if its a school day then go to school and try to learn as much as you can about the place your at. From my understanding schools across the globe have their nation's flag somewhere on campus which will make it very easy to identify which country you are in. Also most teachers have todays date somewhere on their whiteboard or whatever they have in the room (if not you could just ask them what the date it is) after you find out as much about your whereabouts from school you should probably go searching for some sort of newspaper to see the current events in the country  

and to make sure the country isn't at war or something like (If you woke up in a war torn country its A LOT more dangerous) Then after you have collected all of that data try to find your nearest phone and make a call to wherever you previously presided and make contact with your parents. Now if you have gone to a third world country and you simply cannot find a phone then look for your nearest embassy. (For example I live in the US and they have embassies in almost every country, and if you have picked up a new language overnight and you cant speak english translators are almost always at these kinds of places) So at your local embassy you will try to convey your current situation and tell them that your actually from (insert country name here) and tell them your parents phone number, they will call them and boom. Now worst case scenario is that your parents say that they don't have a kid or they don't know anyone by the name of (insert name here) and in that case the embassy will send you off. But most likely your parents will know who you are. If you want any more elaboration let me know, I know I wrote a lot but this seemed like a cool question and I fall down a rabbit hole sometimes :/