This is so "My camera doesn't work" post which usually should get response "Did you turn it off and on again" answer.
But to get in details WHY its not working, it requires details how it was set up to actually troubleshoot
Perhaps some screenshots, camera installation details , your last actions that led to camera being offline, any ISP changes in this period?
What do you mean your app is not connecting to hik connect? You cant login? Please clarify
Cheers,