Hi @mabwana, sorry to hear about this. 
To be able to pair the BSP 10 speaker with your phone again, you will need to set the speaker in pairing mode.
You can pair the speaker with the phone either using NFC or Bluetooth.
To pair the BSP10 with an Xperia™ device using NFC.
- On your Xperia device, make sure that the NFC function is turned on and that the screen is active and unlocked. You can enable NFC in Settings > More > NFC.
- On your BSP10, press and hold down the power button until you hear a beep and a blue notification light flashes rapidly.
- Position your Xperia device in such a way that the NFC detection area of each device touches the other. When the BSP10 accessory is successfully paired with the Xperia device, the notification light turns solid blue.
The NFC detection area is placed on the top of your BSP 10 and on the back of your Xperia device.
To pair the BSP10 with an Xperia™ device using Bluetooth®
- On your Xperia device, make sure the Bluetooth function is turned on. You can turn it on in Settings > Bluetooth.
- On your BSP10, press and hold down the power button until you hear a beep and a blue notification light flashes rapidly.
- On your Xperia device, search for and connect to the BSP10 accessory. When the accessory is successfully paired with the Xperia device, the notification light turns solid blue.
I hope that helps! 