Hi Sheila,
Undetectable devices are one of the common issues that we encounter when using Bluetooth connection. To troubleshoot Bluetooth issues, please follow these steps:
- Select the Start button, then select Settings > Update & security > Troubleshoot.
- Under Find and fix other problems, select Bluetooth > Run the troubleshooter.
Please check the articles below on how to connect a Bluetooth device and fix Bluetooth problems in Windows 10.
Fix Bluetooth problems in Windows 10: FAQ
Let us know if you need further assistance.