Jackie McBride on "Activated theme does not show up"

Hi, educaaeh, & welcome to the WordPress support forum. Looks like at this point you're running twentyfifteen (thank you *so much* for the site link, btw).

If you're trying to activate another theme that isn't showing, there are a few things you can do to figure out why that's the case.

First, try opening your wp-config.php, either in your hosting provider's file manager or via FTP, (preferably secure FTP), & change wp-debug from false to true. This is a serious security risk, so please leave it on only until you've obtained the information you need. Any error msgs will be displayed to your dashboard, but also likely to the homepage when you visit it--thus the waing.

Secondly, you may wish to check for files in your WordPress folder called error.log or error_log. These may contain error log entries that will indicate what the problem is. Additionally, some hosting providers also have aplets in their control panels which allow you to view entries in the error log for your site. These can also prove of great benefit, if present.

Lastly, you can try eliminating all plugins by renaming the plugins folder to plugins1 or plugins.old, (anything you like, really), & then see if your theme appears. If so, it would indicate a conflict w/a plugin. The next task is to see which plugin is culpable. To do that, you rename the plugins folder to its original name, but rename all plugin folders beneath it except 1--Akismet & Jetpack are likely good candidates--& then try to visit the site, being sure to clear your browser cache each time. Continue renaming plugins in this manner until the theme breaks, at which point you know which plugin is causing the conflict.

HTH, & please don't hesitate to paste error log entries here if you have questions about their meaning. You should enclose them in , i.e.,

first entry
2nd entry