My car wont start lost my key so got an ignition barrel and key out of a different car wat do i need to do? plz if anyone can help plz

the original key is coded to your car.
So changing the barrel to have a new key wont help and ill tell you why.
Inside the original key is a transponder chip that is programmed to the cars immobiliser unit.
Attached to the ignition barrel is whats called a reader coil and its job is to read the keys chip when inserted in the barrel to deactivate the immobiliser so that the car will start.
What you need to do is contact a good knowlegable locksmith to provide a new key and code it to your car

go to the rear of the ignition switch you have to look up from under the drivers foot well ,pull off the plug now you see the electrical part of the ignition switch remove the two screws holding it on to the rear of your ignition switch ,lift it off now put the wiring plug into your electrical part of your ignition switch turn that to start the car.now you can start it.the trouble is your steering lock is still on .so now look with care at your ignition ,you should see a pin holding the barrel on .push in the pin to remove the barrel so now you can drive the car.go to a car breakers and get a barrel and key.

Check for obd codes & diagnose them

immobilizer not recognizing key. vehicle will start and cut out immediately. try unplugging instrument cluster and recconecting as they sometimes develope a bad connection due to connector pins being very fine. check connection between ignition barrel and dash cluster. immobilizer built into cluster. if engine control unit has been changed immobilizer won't recognise it, must be adapted using diagnostic reader. this is done by entering instruments [code 17] select adaption [code 10] and channel 00 [erase learned values] and confirm. keys may need to be adapted to immobilizer [only at dealer as key code is needed.

ignition barrel worn or dirt, need a new barrell, try another key or get 1 cut to try and turn, a cut key wont start it, u have to hold the original key very close to barrel to get the code

you will have to get a dealer to cut new keys to code that dealers have access to and then get them to program to car but also erase old keys so vehicle wont start with old keys
or next more expensive option is new keys, ignition barrel and door barrels replaced which are differently same coded key and locks as well as programming and erasing old keys.

Change the ignition barrell.

Is your theft light flashing. If it is try this. I learned this from emission wiz Put your key in turn it on dont start wait 10 mins remove key wait 10 seconds repeat this a total of 3 times. If that dont work try a different key do the same thing. This relearns your key to the ignition it started with Gm cars and trucks from 1999 to to 2006. It is a big problem but there is no recall that I know of. If that dont work a dealer needs to probably replace and reprogram your ignition switch and keys

I am sorry but I am not sure what you mean by ignition barrel, please describe problem without word abbreviations and I will try to help you.