GMC Repair: ignition, gmc sierra, tumblers

Question
2001 GMC Sierra 2500 PU
Insert key in ignition but it won't turn. Its in the lock position and I cannot get it to move.
Worked fine all weekend. Were gone Sunday night.
Monday morning got in vehicle, put key in ignition-cannot turn it.

Answer
You may want to try and spray some light lubricant in the cylinder to see if it will release the tumblers. Also, try to put the key in the ignition and tap on the end of the key towards the cylinder and see if that helps. If all else fails then you will have to disassemble the column, remove the cylinder case and disassemble the case to get the cylinder out and replace and recode the cylinder.