Remove 8 inches of shingles at each side of the valley with a 16 inch nail bar.
How to repair tile roof valley.
If the ice and water shield is missing then you will have to remove the shingles on both sides along the valley put ice and water shield in place and re shingle the roof.
Insert the bar under a shingle and pry upward at a.
Video recorded while doing a tile repair the usual valley repair that leaks when the water run off the valley metal hope you like it.
A properly flashed roof valley should have an ice and water shield installed with roofing felt being properly secured over the ice and water.