I don't know what I did. I changed tires, and when I went to ride tonight I tried shifting down to the small chian ring in front and the cable tension seemed high. It clicked eventually but never shifted down. Any thoughts?

Post this on the Bicycle Mechanics forum and supply much, much more information. You will get abused hereabouts.

Correct, a moderator can move it for you if you ask.

When this happened to me, it turned out to be the left 105 shifter ("brifter") It was about 1 y/o and Shimano's warranty is 2 yrs. Bikes Direct replaced it, but when it didn't match (I had Ice Grey, and they sent a shiny silver) they upgraded both shifters to Ultegra.

Of course, it could be a lot of other things: kink in the cable housing, defective FD, etc.

cable tension settings? LOL

Check to see that the front derailleur cable did not come out of the stop on the downtube leaving the housing perched on the edge of the stop..Next time when you remove the rear wheel, shift the chain to the small chainring and the small cog in back..

The derailleur dropped down and is caught between the outer chainring? This would be pretty obvious but I've missed the obvious plenty of times.

most importantly take your time and sort it all out. If your not mechanical incline have a shop do it.