I removed my Sidebar and want it back

You could have done lots of things, but start with

In pages, look at the right hand side, and see what Template the home page is using, should be one with a sidebar – try other settings from drop-down list to seen if this helps

In Widgets, check that you have widgets set for your sidebar

Re install your theme it will be back.

I used the default page for all but one page and I setup a child template.

What page is used for the default?
Would reinstalling the theme help if I did not change the parent theme?

What happens if you switch to the unedited parent theme?

I switched back to the parent theme and still no sidebar.

How do I reinstall the parent theme?

Re-upload a fresh, unpacked, copy of the theme’s folder to wp-content/themes using FTP or whatever file management application your host provides.

I uploaded a fresh theme but still no sidebar.

I looked and looked and could not see any file that i had changed. Then I decided to switch the page template from the default to the sidebar and wa-la I have a side bar again.

“In pages, look at the right hand side, and see what Template the home page is using, should be one with a sidebar – try other settings from drop-down list to seen if this helps”

always the simple answer once you find it !