Check Bluetooth is Enabled:

Open Action Center (Win+A) and verify Bluetooth is on. Also check if Airplane Mode is accidentally enabled—it disables Bluetooth.

Run Bluetooth Troubleshooter:

Settings > System > Troubleshoot > Other troubleshooters > Bluetooth. Let Windows attempt automatic repairs.

Restart Bluetooth Service:

Press Win+R, type "services.msc". Find Bluetooth Support Service. Right-click and Restart. Set Startup type to Automatic.

Update Bluetooth Driver:

Device Manager > Bluetooth > right-click adapter > Update driver. Or visit manufacturer website for latest version.

Remove and Re-pair Device:

Delete the problematic device from Bluetooth settings. Put the device in pairing mode. Add it again from scratch.

Check for Interference:

USB 3.0 devices can interfere with Bluetooth. Move them away from Bluetooth adapter. WiFi on same frequency band also causes issues.

Conclusion:

Driver issues cause most Bluetooth problems. Updating drivers and re-pairing devices typically resolves connectivity issues.