Unable to flash boot.img in htc one v

I'm trying to install a new rom in my HTC one V. I could successfully do everything with my one V until I upgraded my windows 7 to windows 10. I already have CWM recovery. USB debugging is ON . I try to check if my phone could be detected by entering the command "adb devices" while my phone is switched on, and it shows me that my phone is connected. now I restart my phone into bootloader mode, then I select fastboot, but it doesn't show fastboot usb , which previously used to show. I try to check if my phone is cooected, but no device shows neither with "fastboot devices" nor by "adb devices". rebooted phone in fastboot, opened Device Manager -> Universal Serial Bus Controllers -> Unknown USB Device (Device Failed Enumeration) with a yellow triangle on the icon. Downloaded latest_usb_drivers i.e. google usb drivers, and updated its driver using it, it says WINDOWS HAS DETERMINED THE DRIVER SOFTWARE FOR YOUR DEVICE IS UP TO DATE, but yellow triangle persists, and still not discoverable in fastboot. please help P.S. my bootloader is unlocked