Sometimes, when you connect a pen drive to your MacBook Pro, the drive won’t show up in Desktop, Finder, System Information, or Disk Utility. This drive’s inaccessibility could be due to a variety of reasons. For instance: The pen drive may not be appropriately connected to your Mac.The USB driver is corrupt or outdated.The formatting of your pen drive is not compatible with Mac.macOS settings show the pen drive on Desktop/Finder as disabled.The pen drive’s file system is corrupt.The pen drive may have bad blocks.The USB port may be blocked or damaged.The pen drive components could have undergone physical damage. In such situations, you can’t access your pen drive and its stored data. You need to troubleshoot the issues to access the drive and its stored data. The next sections describe the methods in detail. 1. Resolve the Pen Drive Connectivity Issue Possibly, your pen drive has a connectivity issue that makes it inaccessible on your Mac. So, you can try the following to fix the connectivity issue. Reconnect the pen drive to the USB port on your Mac. If this solution works, it implies the pen drive was not appropriately connected to your Mac.Connect the pen drive to another USB port on the Mac. If it works, it connotes the last USB port on your Mac is damaged.Connect the pen drive to a different Mac or use a PC. If the pen drive works on another Mac, then update the USB driver on your Mac. If the drive works on a PC, then copy data to the PC and format the drive to exFAT; this formatting works on both Mac and PC equally. You can also format the drive in FAT32, but it won’t allow storing of files with size more than 4 GB. Finally, restore data to the pen drive. Now, you could access data from the pen drive by using the Finder window on your macOS. 2. Check whether the Pen Drive Is Accessible When you can’t see your pen drive in Desktop or Finder, use System Information to check whether it is accessible. Steps are as follows: Go to Apple menu > About This Mac > System Report.From the sidebar, navigate to Hardware > USB.From the right pane, check the visibility of your pen drive. If your pen drive is visible, it implies you need to perform other troubleshooting steps to access data from the drive. Else, the drive has physical damage; consult a data recovery service. 3. Fix macOS Settings to Show Pen Drive on Finder & Desktop In case the pen drive is visible in System Information but not in Desktop or Finder, then do the following: Open Finder from Dock. From the Menu Bar, navigate to Finder > Preferences.Click the General tab. Under “Show these items on the Desktop,” ensure the “External disks” checkbox is selected. Click the Sidebar tab. Under Locations, ensure the “External disks” checkbox is in the select state. Now, both Desktop and Finder will show the connected external pen drive on your Mac. 4. Mount & Repair the Pen Drive Using Disk Utility If the pen drive is visible in System Information and the macOS Finder and Desktop preferences are in the correct states, perform the following: Open Disk Utility, then click the View icon from the top and select View All Devices.If you could see the pen drive listed on the sidebar in grey, then select it.Click the Mount tab. If the drive doesn’t mount, then click the First Aid tab.Click Run to begin the drive repair process. Now, you could access the pen drive and its stored data. In case the repair process is unsuccessful, recover data by using a Mac data recovery software. Finally, erase the drive using Disk Utility and restore the recovered data to the pen drive. 5. Free Recover Data from the Pen Drive You can use a free Mac data recovery software to recover data from the pen drive when you could see the drive in the greyed-out state in Disk Utility. Launch Stellar Data Recovery Free Edition for Mac software, select the pen drive, scan it, and recover data to your Mac. Watch Video - https://www.youtube.com/embed/5WMyLK345bc Conclusion Now you know how to recover a pen drive that is not detected in your MacBook Pro. You can start by checking the USB connectivity, verifying its accessibility status from System Report, setting up Finder preferences, and even mounting and repairing the drive. When nothing works, you must use a free Mac data recovery software to retrieve inaccessible data. Finally, restore the recovered data to the pen drive.