What error message do you get? Please quote it word-for-word, unedited, verbatim.
The first time, I got a message that Lightroom was unable to read the card.
Since then, I get "Importing Images" on the screen and a stalled progress
bar. No images appear and the progress bar does not change.
Possibly, your card reader is bad, or your USB cable/USB Port is bad, or the card is bad. Try a different card and different hardware to see if the problem goes away.
I was able to import images into iPhoto so the card is fine and the port is
operating as per usual. It appears the problem is in Lightroom.