As many important files are stored in the USB drive, you may consider to encrypt it with BitLocker in your Windows 10 laptop. However, you might find that BitLocker Drive Encryption option is missing from the control panel where BitLocker feature can be enabled normally. At that time, you need to check that if the installed Windows 10 is the edition (Windows 10 Pro or Windows 10 Enterprise and Education) which supports BitLocker feature first. If it is, you can try the following way to recover the missing BitLocker in control panel.
Step 1: Enter "services.msc" in the search box of the task bar and click the services.msc option.
Step 2: In the pop-out Services window, choose "BitLocker Drive Encryption Service" option in the right panel.
Step 3: Tap "Start" button under Service status in the BitLocker Drive Encryption Service Properties box.
Note: After tapping Start button, a start-service window will be popped out.
Step 4: Select "Automatic" option in the drop-down menu of Startup type. Then click "OK" to save the change and BitLocker Drive Encryption option will be shown in the control panel again.
Tips: If the way above can't solve the problem for you, there might be something wrong in the system and you could try to reinstall it to recover BitLocker feature in control panel.