I own the iphone 5C (Verson iOS 10.3.3.My original apple id and passord were reset. However, now the iphone cannot be activated because the activation server cannot be reached. Please help.

I am having problems activating my iPhone 5C. It is giving me the message Your phone cannot be activated because the activation server cannot be reached.

My original apple id and password at the time of purchase was reset because my daughter had tried to access it. I have been using the phone under a new apple id and password but after I have replaced the battery I cannot activate it. I have also up graded it to Version iOS10.3.3

Please assist