i accidentally deleted lunch pad form the dock. How do I find int and replace on the dock. Thanks.

Read this:

Use Launchpad on your Mac - Apple Support

It says that you can activate it with three fingers and your thumb on the trackpad, and just pinch them together. When it’s active it should show up temporarily on the dock. I think you should be able to keep it on the dock by selecting the icon and selecting an option to keep it on the dock. I’m not at a Mac now so I can’t test it.

Hi,

The Launchpad.app is located in your /Application Folder.

Easiest way is to drag it down back into the Dock.

Just a follow-up for completeness. I got to my MBP and tried the 4 finger pinch and it did bring up Launchpad. However, simply bringing up Launchpad doesn't temporarily place the Launchpad icon on the Dock like launching an application (and where there's a "Keep in dock" option).

What everyone else said about going to the Applications folder and dragging it to the Dock works.

Go to your Applications folder and drag the Launchpad icon down to your Dock.