Unable to remove key from ignition

Its the ignition switch.

check oil to see if there is rad fluid in it. if there is you have a cracked head or head gasket. if no rad fluid in oil, check for a spark.pull out a spark plug attach spark plug wire hold close to engine block with gloves and turn over engine. it is best to have someone with mechanical know how to do this,i.e. friend or nieghbor

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Could be a problem with the cable to the shifter. The shifter is supposed to be in park to lock the ignition switch and remove the key.
Could also be something jammed in the lock cylinder.

Sounds as if the ignition cylinder is bad. You will have to replace it if the key is stuck. It is a lot easier to replace with the key in the on position as that will be required to remove the cylinder. If you get the key out and then the cylinder will not turn, replacement of the cylinder will be more complicated

The first thing I would do is clean your battery connections very good. you may have to remove the plastic covers off the cable ends to get them cleaned good. Also make sure you get the connection bolts tight.

Worn key or if auto transmission it could be the selector switch.

If manual try wriggling the key in , out while turning etc

The ignition has an interlock that will not let you turn the key all the way to OFF until the transmission is in park.
This is done via a sensor either in the transmission itself, or on the shifter.

With the car off, step on the brake and shift from Park to Reverse, then back in to Park. You should hear a faint "click" as the interlock engages. If not, then your sensor (switch) may have failed.

go to the dealer with the vin and proof of purchase and they should be able to cut a key with this information you will also have to have proof of ownership.

On many cars, if the battery is dead, it locks the key in the ignition. Put a battery charger on the car or replace the battery and give it a shot.

Good luck.