I've been working on a mobile game in Unity for over a month, saving all my work to OneDrive. Today I restarted my computer and when it loaded back up I tried opening my project and it failed. I looked through my OneDrive and half my files are missing! I've been on the phone with Microsoft support all day and I can't get those files back.
I have the apk file for the game loaded onto my phone. Is there anyway to reverse build this thing back onto Unity or just get the files back from the apk file ?
If by APK you mean Android's APK file you can just 'unzip' it and get at least you xml files and other resources such as images. All classes will be packed to classes.dex file, which can be converted to Java's JAR by dex2jar tool. However JAR will give you only Java's binaries. You could further de-compile them to Java files, but they are not going to look pretty or very readable.
Well, at least you can recover you XML layouts.