Whenever I open iMessage and FaceTime, it says "error during activation"

I recently changed my password for my Apple ID and I somehow turned off iMessage, so I had to put my information into it again to sign in. I have tried a lot of things that many people have said worked for them, but I have no luck. Also, whenever I open iMessage, I can see my messages for a few seconds and then it goes back to the sign in page. I have checked to make sure my ID and password are correct, and I know they are, because if I put it in wrong, it tells me I may have the wrong information. I know this has been an ongoing topic, but it seems like it will be fixed easier for some people, and while I have tried almost everything, I still have no luck.