shifter knob stuck!!

the knob gets stuck. when i put the car in park the key will not come out of the ignition. The button on the shifter gets stuck when i push it in. What is it? how much does it cost to get fixed? can i do it myself? hellpppp!!

I solved my similar prob , by spraying W D 40 down into the shit linkage cable after removing the knob via pulling the U- clip below the tT handle and above the shifter shaft ! try that if the thumb button is hard to depress or is sticking !