Deleted Walk workout on my Apple Watch

There have always only been two walking workout types, indoor and outdoor. The most recent workout type you used should appear at the top of the list.

Workout types on Apple Watch - Apple Support

You may also have customized it (i.e. set it to 40 minutes). See here for information on how to do that:

Create a custom workout on Apple Watch - Apple Support

CPW, To my knowledge you can't replace just part of the Apple Workout App. It's all or nothing. One other option you might try is to power down your iWatch for 30 seconds and power back up.

Restart Apple Watch - Apple Support

Hello CPW, On your watch Press the digital crown and look for App Store App and open it. Then press the search icon in upper left corner of watch screen. With your finger put in each letter of WORKOUT and press search. The Apple Workout app should come up for you to download back onto watch.

CPW wrote:

How do I get it back? I scrolled down through the full list of activities and Walk is not shown in the list.

Do you mean the "Time to Walk" workouts which are a feature of Fitness+?

Use Time to Walk or Time to Run - Apple Support