[Q] i need help installing nexus 7 2012 to stock with no backup topic

hello, this is my first post and I'm fairly new to the android community.

I need help restoring my nexus 7 2012 back to stock. I had the Paranoid Android ROM, I was trying to go back to stock in hopes of installing Kit Kat but I didn't back up first, now I'm stuck. I can still access TWRP but no luck with my computer recognizing the nexus 7.

Any help would be appreciated..

thank you thank you
jude