My ex

Me and my ex have been friends forever since 2010 we split because of long distance a long time ago, but we always check on eachother and help eachother out with advice we never lost contact..

so I messaged him for the first time in four months and messaged him to see how he is. He ended up opening my messages and didn't reply at all... he asked me "who's number is this I got a new phone" I said my name he read it never replied... I'm so confused because he's never ignored me or anything ? I messaged him again yesterday he opened it and didn't reply... wtf did I do? I'm kind of hurt tbh because he has helped me through so many deaths and relationships, friendships. Always have been friends first. Now all of the sudden he ignores me ? Like I'm nothing..

Does anyone know a reason for someone you have been best friends with for almost 10 years to just totally ghost you? Because I am lost?

(I didn't know what group to post this in wasn't one that fit really)