About the SimCard locking

so i really don't know if i am in the right sub, but let's hope so

so i bought the S5 from germany about 3 days ago, when i returned back to my country, i noticed that the phone ONLY accepts european simcards so i am locked out of using the phone for calling or texting or anything

so i searched alot and found an app which required rooting
and i found some website which will provide codes to unlock

so i am really lost here, what should i do?!