My 2006 monte carlo shift knob get stuck and when i place the car in park i can not get the keys out of the igniton

I am not sure on that exact shifter but usually there is a screw or a retainer wire in the side of the handle part, If you pull the shifter all the way from the dash area you can look at the front of it, The retaining wire or screw will not be very big and it's not really easy to see but you can see it when you look closely.
If it's a screw you simply take it out and lift the handle off, The button will stay on the shift rod on most cars.
If it's a wire it may push in or pull out either one, Try to push it in with a small flathead screwdriver first, If it will not go in, It likely comesw out, You will have to carefully pick it out with a small tool.
The handle will come off same as a screw type.
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You can go to Wal-Mart and get a mechanics pick set for pretty cheap. It is made by popular mechanics or stanley and they come in sets of three or four, They have different types, Straight, 90degree, 45degree, and 'J' hook.
One of these tools should get the retainer wire if thats what your car has.
Good luck.