If you're accessing your course from a mobile device or tablet or from within a small browser window, Blackboard will collapse the sidebar by default. To expand the sidebar, click the blue area at the side of the screen.
If you don't see the blue area to expand the sidebar, try enlarging the browser window.
You might also want to check that your browser window is not zoomed in as this will also cause Blackboard to hide the sidebar.
RELATED KNOWN ISSUE
A current software bug results in the pull-out tab appearing on the far right of the screen for some browsers and operating systems. You must scroll your window to the right to see it.
Unfortunately, even if you locate the course menu on the right side of the page and open the menu, a page reload may close the menu again and force you to scroll over to the right again to re-open the menu again.