Hi maidinregina2021,
Glad to have you join the Community. It's essential you're able to track your mileage using QuickBooks. Don't worry, I'll be happy to give you a hand so you can get back on track with tracking and managing you mileage.
The Mileage module can be found by hovering over Expenses on your left navigation menu. From here you'll see an option for Mileage. In the event that this issue is being caused by browser-related issues, I recommend clearing cache and cookies. Clearing cache and cookies helps with fixing most browser-display/functionality issues. You can do this by following the steps in this article: Clear Cache and Cookies. If you're still having issues after verifying the info above, I recommend contacting our support team so they can take a closer look at the issue.
If you have any other questions, feel free to reach out here. I'll be here.