Walkthrough below:
Go left down beach. Take magnifying glass next to crate.
Go right. Go towards water. Click bottle, read message. Go back.
Go right. Take metal.
Go right to lighthouse. Go straight to woods.
Go left. Take hammer from under tree. Go back.
Go right. Click rock at left middle. Take metal. Go right.
Take log. Go back to lighthouse.
Click left to go to lighthouse door. Click loose brick. You can break it with the hammer and get the third metal.
Go back to the beach. Click the brown patch next to the sign. A fire should start.
Go left. Click the crate. It will open with the hammer. Take the rope.
Go back to the fire. You should get a finished grappling hook. Go to the lighthouse door, click the lighthouse to fling the grappling hook. Click the rope to climb to the top.
Congratulations! You have cell service.