How do i restore Safari

What happened to Safari? Errors? Messages? Details? High Sierra?

Safari is part of macOS, and fairly well protected against unintentional deletions.

Add-on apps and Safari extensions can sometimes cause issues with Safari.

Occasionally preferences can get corrupted. Create and try a different (new) login, as a test.

If Safari is missing not in your Dock, drag it from Applications back into your Dock.

But to “restore” Safari, you would reinstall macOS, and re-apply any subsequent Safari patches.