KEYS WOULDNT TURN IN THE IGNITION .. WHATS THE PROBLEM?

check your ignition switch/linkage.

The BCM (body control module) is seeing the wrong passkey code. You will have to find out what passkey code is being used in the new steering column you installed them see if the BCM can be reprogrammed for it Some can not be reset.

Sounds like you need to reset your alarm kill switch, which should be located near the driverside kick panels. GL.

Here's the link and I'm sure you will get the solution of your problem 1999 Peugeot 306 Cabriolet Workshop Service Repair Manual

If you have too many keys on your keychain, the extra weight can wear out the key tumblers in the ignition switch. If so, you will need to replace the ignition switch key assembly with a new one.

I bet you your stearing wheel is locked, so try this.....When you put the keys in the ignition rock the steering wheel left and right while trying to turn the key....This is a common thing with most vehicles

Your car uses a transonder key, a key with a small chip embedded inside. The transponder is matched to the immobilizer unit in your car. When the key is inserted into the ignition, the immobilizer searches for that transponder, if it's not near the ignition, the car will just keep turning over and not start. Your only real options are to replace the steering lock or buy a transponder bypass unit, which I do not recommend. Just do a google search.

try putting the shifter in N and move the pressure off the wheel.

Sounds like an antitheft problem I would start with the antitheft system. Usually when you only have one key all keys have to be programmed together even the original. When you have more than one it is easy to program additional keys.

Get a Trouble code free at Autozone or similar store. It may be the catalytic converter thats bad.