2003 Blazer Ignition

I have an 03 Chevy Blazer, I had a lot of problems with it
but finally got everything that was wrong, fixed. After
putting in a new battery, I started it up to see if it would
run and the key turned and I was able to start it right up. I
shut it off to try once more and ever since then, the key
won't turn. The ignition cylinder will turn backwards even
without a key, but no matter what I do or try, the key will
not turn forward what so ever. I read that if you want to
remove the ignition cylinder you have to be able to turn it
at least to the on position. I'm lost and have nobody to
help. I have enough money to buy a new ignition cylinder
but not to call a lock smith. Help please