1999 Ford Taurus wont shift

If it the sensor went out why does it still shift when I manipualte it. Also about how much would it cost to fix this type of issue. Also where is the sensor located?
Any advise is taken gratefully. Once I align the ignition switch I can shift into gear with of course my foot on the brake as normaly.

Your telling me it is a transmission porblem but I am not having any problems with the transmission it is with the shifter. I know how to manipulate it to go into drive and all other options and the transmission is not slipping. Do you have a better answer? Could there be a possiblity that it is something loose in the steering column? Please email me a bears0559@verizon. Net I have not gotten an email from you like my brother does?

Where is that located could you tell me I just want to be knowlegdable. Although I am a woman I need to know these things. I know I can't fix it but would still like to know. How much would estimately cost me to fix this problem? Thanks for you answer I really appreciate. Liz