Do you see the camera from the explorer/finder?
What is your OS and which exact version of Lightroom are you using?
A far better solution is to try using a card reader, as the direct camera method is the least reliable and the cause of many threads in this forum, they nearly all clear after the card reader method, The USB lead can also be a cause, but the card-reader is the most reliable method to import photos.
I suspect these are connection or camera issues most of the times.
So far I used the direct connection with all my cameras and never had any issues.
Not to forget: Most of the card readers are also connected by USB - even most of the internal ones - so there's not really a difference between the direct connection and a card reader.
Direct connection with the camera requires camera battery power. Connecting a card reader uses USB power from the computer. It is quite possible that your camera battery is low. Some cameras will not allow downloading if the battery is low. Try charging your battery. Better still, use a card reader to avoid the battery level dropping during import which could corrupt your images.
The camera should also show up in your OS (Windows or OSX) without Lightroom started. If it does not, you have a camera/computer problem and not a LR-camera problem.
At least with windows, I have sometimes the problem that one or the other USB port "mutes" for a specific device. So try also other ports.
The camera was not showing up in the 'finder' window. I went to preferences and found a way to make it show up again. Every thing is fixed. Thank you for the suggestions.
I tried a new cord, and a different usb port
I checked the battery.
I checked other programs to see if the camera would show up. No luck to all of those options.
I tried this forum, and then I went to the help tab on the iMac. That led me to check what preferences were checked. And that is how I solved the problem. Thanks everyone!