I have read how to release key from switch by using ignition interlock swith in steering column. what I need to know is how to fix original problem.

 

Well the only way to fix it is to replace the ignition lock cylinder, you can do it yourself, but the degree of difficulty is up there. Your other option is to have it replaced by your dealer, it runs around $300.

GM was/is covering the replacement, so you want to check with your dealer's service department.

Here's a thread on replacing the lock cylinder.

https://www.chevyhhr.net/forums/problems-service-repairs-42/ignition-cylinder-lock-20649/

 

Since you didn't state the year of your car, it's hard to tell if you might be still covered by the GM repair order.
I remember something about different year models having different time periods to get the repair done by GM(free replacement)
I had mine replaced by GM, and recall the letter stating I was eligible for a replacement until some time in 2014.