quote Simon the Nekonin

What a second...when you go to the white bridge...is that when you warp to Eldin? Can someone give me instructions? I am a little confused.

The bridge piece you find in Gerudo Desert is the big missing chunk that will fix the Bridge of Eldin. It's the top-most warp in the Eldin Province. If you haven't beaten the Shadow Beasts at the opposite side of the bridge to open the warp, you have to go around through the Lanayru Province to get to the other side of the bridge.
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Yeah, if you can't already warp to Hyrule Field, Bridge of Eldin there are some Twilight Messengers to defeat on the north side of the bridge. Defeat them first then you can go back to Greudo Mesa and get the piece of bridge and place it in the Bride of Eldin
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I hear there is a way to miss it so I suggest going back to the bridge and fighting the Shadow Creatures.
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also you must of killed the shadow creatures to make the warp possibe to warp you
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its the brige where you fought the guy on the boor to free colin you had to fight three shadow monsters as link and you were heading to lanayau to purge that land of the twilight warp to hyrule castle then go to kakariko with out warping you will find the shadow monsters kill then done
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