Too bad :-( , how did you managed this ? Was engine cold, did you spray some de-seizer the night before ?
However, the good news is that you can start it "on 3 legs", the engine will start a bit shaky, specially in colds, but will soon stabilize as the fourth cylinder (always count them FROM the pulley) will eventually fire-up. You'll propably notice some blue-ish/white smoke due to incomplete gasoil burnt in this cylinder, this will disappear aswell.
There are kits available to extract broken glowplugs,google will tell you ...
BTW, you don't need to remove them for resistance checking...
BRs, Bernie
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