Took the igntion barrel out,had it serviced by locksmith,installed but it won't start.

Needs an auto locksmith to replace and reprogram.

https://www.google.com/search?q=mobile+auto+locksmith+near+me

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Should it still start after bypassing the lock and using the igntion control module with a screwdriver?
Your best bet take it to a qualified repair shop !

best place for this is a service dealer
normally the immobilizer works around the barrel and is activated by the proximity of the fob key
if you were to get a locksmith to install a new barrel , it would have to be reset to your key so that you could insert the key and activate the immobilizer system
another way may be to get the entire lock system from a wreckers and have it reprogrammed by a locksmith or service center to your key or a new key

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

igntion switch ? you saying key and tumbler
thought it it is part of the igintion barrel

not much information out there on that question

with the barrel out might be one for a locksmith

you tube
Ignition removal for the Crown Victoria

well it may not be the barrel but most likely the connection at the end of the barrel will be faulty where the wiring is.

the barrel will be available at any locksmiths and they will do the job in probably five minutes. take it to a jayco service centre or any caravan repair shop as the keys and barrels are common.

YOU MIGHT TRY REMOVING THE KEY REMNANT WITH NEEDLE NOSE TWEEZERS ALSO KNOWN AS JEWELER'S TWEEZERS TAKE BOTH PIECES TO LOCKSMITH FOR A REPLACEMENT

Could be one of 2 problems: Steering torque lock is stuck, try pulling steering wheel in both directions while trying to turn key.
OR
The barrel of the ignition key is damaged/worn out. I have changed the barrel on my Merc and it is a real headache. Would recommend a locksmith to do it. If you want to do it yourself,

1) Remove all facia covers starting with the 2 small screws at the hand break release and work your way towards center of car.
2) When lock is visible, you will see a locking pin on the steering lock shaft (this pin is titanium and cannot be drilled out). A slot needs to be cut from the pin to the edge of the steering lock shaft.
3) Remove gear lock cable from switch.
4) Remove lock from steering column (brute force is needed!)
5) With heated screw driver (small Phillips) push holes through square profiles (3x) at the back of the switch, wiring side, and remove screws to expose wiring switch; N.B. align key-way before removing switch box, otherwise you will need an auto electrician to re-wire.
6) Take metal part of switch to a locksmith to locate circlips that secure the barrel in the switch. Slots have to be cut into the black surround which is titanium and cannot be drilled. (This part of the job you cannot do yourself without specialist tools.) Remove barrel.
7) Purchase new barrel from MB Dealer with new key, and repeat the above procedure in reverse.
8) As I said - take it to a locksmith!

Good luck! It took me and the locksmith 3 days!

try anoth igntion key, if not a good moble auto locksmith should be able to diag this, if he can't you'll need to tow it to your local GM dealership. It could be the igntion cylinder, but there is more items involved in the security system besides the igntion cylinder & you need the proper test equipment for testing.