Thanks for trying some troubleshooting to get the side bar again, @accounts92.
You can use the Hide button to remove or un-remove the side or left navigation tool. Kindly click the Burger (three horizontal line) icon beside your account name.
Check out the screenshot below for reference:
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For future help and resources, here are some links of our articles, videos, and blogs:
Keep me posted if you have additional questions. Take care always and have a wonderful weekend!