Default Lg support tool problem help asap

So i have a brick lg optimus l9 p769
i am trying to flash V10D_00.kdz into lg support tool or r&d test tool (sorry I'm nooby with this) but it seems that when i connect my phone into s/w mode or download mode ,my computer dosent reads it i just says usb device not recognized. the lg support tool or r&d test tool stops at 15% to connect my phone.

Please i need help ASAP , im still paying for this phone and theres no point of paying it if i can't use it.

sorry for my bad english