Hi FBN. I'm Greg, 10 years awarded Windows MVP, specializing in Installation, Performance, Troubleshooting and Activation, here to help you.
Many Bluetooth problems right now are being solved by updating to the latest version of Windows 10 so if you want to try that first skip to Step 11. Otherwise try all of these steps in order, reporting back results for each so I know what else to suggest if necessary:
1) See if you can System Restore to a point before the problem started: https://itechhacks.com/system-restore-windows-11/
System Restore is your first line of defense and can take you back to a point before a problem began. If it doesn't help then you can undo it. Read about it first in the tutorial above and then try restoring to just before this started. If System Restore is not enabled on C drive do that now so it's available in the future.
If the problem repeats or System Restore doesn't work then check which Windows Updates were installed at Settings > Update & Security > Windows Updates > Update History, uninstall them there or System Restore again, then immediately check for and block the Updates with the Hide Updates tool explained here: https://www.tenforums.com/tutorials/8280-hide-show-windows-updates-windows-10-a.htmld in Device Manager reached by right clicking the Start button.
2) Try Updating the Bluetooth driver from the PC maker's Support Downloads webpage for your exact model. Install it even if it's the same or newer than the one in Device Manager reached by right clicking the Start button. While there check that you also have the latest chipset, BIOS, display, network, USB and all other drivers, compared to the ones presently installe
3) Right click Start button to access Device Manager, locate Bluetooth device (if necessary from View tab Show Hidden Devices), on Driver tab see if Roll Back is available, if not try Update Driver, first automatically, then Browse, then Let Me Pick to try all previously installed Drivers. If these fail Uninstall the Driver, restart PC to reinstall. If the BT driver is not there, access the View tab in Device Manager to "Show Hidden Devices."
4) Make sure you're pairing correctly as shown here: https://support.microsoft.com/en-us/help/15290/windows-connect-bluetooth-device
5) Try Fixes here which are all working:
https://allthings.how/9-ways-to-fix-when-windows-11-bluetooth-is-not-working/
https://www.lifewire.com/fix-bluetooth-not-working-in-windows-11-5191455
https://gadgetstouse.com/blog/2021/09/26/fix-windows-11-bluetooth-not-working-audio-lag-connection-issue/
https://windowsreport.com/windows-11-bluetooth-not-working/ (Avoid ad links which intrude into editorial copy, especially avoid Restoro, PC Repair Tool and Reimage ads)
https://www.techlicious.com/how-to/how-to-fix-bluetooth-pairing-problems/
https://itechhacks.com/bluetooth-not-working-windows-11/
https://www.guidingtech.com/top-ways-to-fix-bluetooth-not-working-on-windows-11/
https://www.droidwin.com/fix-bluetooth-not-working-issue-in-windows-11/
https://www.digitbin.com/fix-bluetooth-not-working-in-windows-11/
https://techwiser.com/fix-bluetooth-not-connecting-audio-lag-windows-11
https://www.youtube.com/watch?v=wEgslnYl2OQ
https://www.youtube.com/watch?v=vH095EanlJo
6) Try the Bluetooth troubleshooter at Settings > System > Troubleshoot > Additional Troubleshooters.
7) Try turning off Fast Startup at Settings > System > Power & Sleep > Additional Power Settings > Choose what Power buttons do > Change settings that are unavailable > uncheck Fast Startup.
8) If this was caused by a Version Update then for 10 days you can roll it back in Settings>Update & Security>Recovery and then hide it until it matures using the Hide Updates Tool which is explained more here: https://www.droidwin.com/how-to-stop-only-a-specific-update-from-installing-in-windows-11/
If that doesn't work you can also Go Back in Repair Mode as shown here: https://www.elevenforum.com/t/boot-to-advanced-startup-winre-in-windows-11.425/
You can also let the Updates install again as they may not cause the same problem, then if they do use one of the above methods to remove and block them.
9) If you think the BT adapter has failed, you can replace it easily with an inexpensive USB nano adapter like this one: https://www.amazon.com/ZEXMTE-Bluetooth-Receiver-Transfer-Wireless/dp/B0775YF36R/ref=bmx_1/144-8846981-0178846?
10) Run System File Checker/DISM in WIndows 11: https://www.elevenforum.com/t/use-system-file-checker-sfc-to-repair-system-files-in-windows-11.720/
11) If that doesn't fix it then you can do a Windows 11 Repair Upgrade which reinstalls Windows while saving your files and apps in place, brings it up to the latest version by the most stable method, takes about an hour and resolves most problems: https://www.elevenforum.com/t/repair-install-windows-11-with-an-in-place-upgrade.418/
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.
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