Why is the new theme not appearing in Magento 2 after installation?

You did a successful Magento installation, the base theme is showing up and you are all good to go. Then you uploaded your theme and updated it from the Magento backend. Still, it’s not showing up. This is a problem that might eat up some of your time. Usually, a straightforward solution will fix it.

Once you’ve created the theme in the right folder, just run these commands: 

php magento cache:clear

php magento setup:upgrade 

php magento setup:di:compile and 

php magento setup:static-content:deploy --theme {vendorName}/myTheme2

That should do it!