I've requested that this thread be moved to 7" Kindle Fire HD Q&A, Help & Troubleshooting
The Kindle Fire HD 7 First Aide Tool has drivers,
but you should also see Windows Device Drivers and the Device Manager
note: written for original kindle but steps are similar
install drivers with First Aide, reboot pc, connect Kindle, update drivers in Device manager.
if that doesn't work, when updating drivers select drivers folder from First aide files, may need to uninstall old drivers, and reboot pc to get it to work.