Hi Debbie,
There could be several reasons why your phone may not be recognized by a computer. I found an article that goes through all the possibilities and gives you solutions for them.
[link|https://themobilequery.com/lg-v40-thinq-wont-connect-to-pc/|LG V40 ThinQ won't connect to PC? Just do this|new_window=true]
In a nutshell, here's the list.
# Default USB connection type on the phone is "USB Charging".[br]
Change the setting to "File Transfer" or "MTP".
# Use Developer Options to change the default connection type as listed above so it stays that way.
# Try a different USB port on the computer.
# Check the charging cable.[br]
My addition: I have seen cables that are for charging only and don't support data communication.
# Update your MTP driver on the computer.
# Use the Android File Transfer app for a Mac.
# Run Windows Device Troubleshooter.
# Try a different PC.
# Take it to an authorized service center.
Hopefully something in there will help. Let us know how it goes!