Deleted Safari

Safari is installed as part of your Mac's operating system. I cannot be deleted or individually installed. You will find Safari in the Applications folder. If you drag its icon down to the dock that will create an alias there for you to use to access Safari.

If necessary, do a backup, preferable 2 separate ones on 2 drives. Boot to the Recovery Volume (command - R on a restart or hold down the option/alt key during a restart and select Recovery Volume). Run Disk Utility and select First Aid. Then re-install the OS.

Reinstall from macOS Recovery

OS X Recovery