I generated a signed APK of my app to send to my friend. Before sending it I went back into Android Studio to keep working on it but the app wouldn't open up. It was as if files were missing from it. Apparently this isn't the case but I didn't modify it and it seemed the app folder that was generated was lost from my application. I tried putting the folder back but it didn't work.
How can I load my app back into android studio from the signed apk file that I created?
Sorry my friend, unfortunately its imposible to load app back to androidstudio from an apk. Unless you had a project copy you missed. You can try to decompile apk and get some classes and resources.