Android Studio: I accidentally deleted my app.iml file from my project, how do I add it

I opened the "Gradle projects" pane on the right, alt-clicked the project, then "refresh Gradle project" and all was fixed.

Got it....I just imported the project like it didnt already exist and it fixed itself.

This might help too if you have not save the project.

Just copy and paste app.iml file from any project inside app folder of your project(if you already have saved the project then copy from that) and then restart the project.

This will help, msg me if problem occurs.