How to fix VS Code that’s not working normally

Today my VS Code doesn’t work like usual. When I try to press “!” on a HTML file, it doesn’t show “!DOCTYPE HTML” and the other normal HTML Format. After that, I write the format manually (doctype, then html, head, /head, body, /body and so on….) and coding the normal way I used to do. The HTML still show normally, but my VS Code no longer accept “!”.

Why that happened? Any help will be appreciated, thanks!