shifter cable out. HELP

[jl_thornburg]

first, I have an automatic transsmission. I was getting gas after normal driving, when I went to put it in drive the shifter moved freely and would not shift the tranny into drive. We jacked up the car and manually put it in drive to get it home, so the tranny is fine, but I don't know about the cable. anybody know what to do???? cable, linkage, shifter??????