today I made a big mistake I decided to change the glow plugs in my td4 I worked from right to left first 3 cam out ok but the last one well the threaded part came out but left the inner core part in and at that it broke as well so it is in the head with no way of getting it out any idea's are welcome or is it a head off.

I had the same on my TD4 FL1 and tapped the electrode through into the cylinder, removed the injector and put a vacuum cleaner tube in the injector hole and at the same time used compressed air through the glow plug hole to dance the broken bit around until the vac could get it.
The whole process took 2 hrs but eventually worked. The problem is the injector hole is 7mm and the piece your trying to remove is 6mm so it's difficult.
Read my posts as I had to drill out threaded bits too. Hope this helps as I too was full of dread thinking the worst.
I borrowed a small compressor of a friend with a blow gun attachment to do this, good luck Alan.

I will get the son in law to try I have heard about knocking it into the cylinder and getting a magnet to pull it out , I have a big compressor so should be ok
thanks for the advice

I have decided to leave it in