Oops. My apologies.
I'm pretty sure most people have been experiencing this bug. Although, someone from MC Forums has found a fix. Here's how you get your worlds to save:
1.When you quit to the main menu, exit the app immediately.
2.After exiting, close MCPE in Taskkiller, or the Multitask bar.
3.Then open your world again, and all things you've done should be saved.
You have to create a stonecutter. Then, tap the stonecutter and a menu will pop up. You should be able to craft 'em from here.