in device manager it shows adb android
nexus 5 16gb ----4..2.2
Oh you mean your PC isn't recognizing the device?
Make sure android sdk with platform tools and usb_driver is installed on your PC and then,
Follow these steps:
1. Connect your phone to your pc and head over to control panel---device manager and select your phone from there.
2. Right click on it and select update driver software.
3. Now select "Browse my computer for driver software"
4. Put this path "C:\Program Files (x86)\Android\android-sdk\extras\google\usb_driver" (C:\Program Files (x86) may differ on your pc depending on where you have installed the SDK)
5. Put a tick on "Include subfolders" and click next.
6. The drivers will be installed again and ADB will recognize your device.
Make sure you accept the authorization request popup on your device when you connect to your PC.