I can help you have the left navigation menu again, @marsha-sabol.
You'll have to click the Hamburger (three horizontal lines) icon beside your account name. That option helps hide and un-hide the left navigation menus.
For visualization, please refer to the screenshot below:
For future reference, check these links for our articles, videos, and blogs:
Keep me posted if you have additional questions. Take care always and have a wonderful weekend!