Decompile a forge mod?

I need to decompile a mod that uses minecraft forge.  I have the obfuscated class files for it but somehow my mod folder got half cleaned when i did getchangedmodsource (I have all the folders but everything inside of them is missing)

I tried throwing the class files into a jar like I was installing a mod and installing forge using that jar, but forge removes the files from the jar before it starts decompiling

If anyone knows how to do this it'd be a great help, because otherwise I have to copy all the obfuscated code and then deobfuscate it manually, and seeing as I have over 20 files, I'd really rather not do that, especially because I don't have the source memorized, so I don't know what methods I should have in some places

Extract JAR file somewhere, then get fernflower from <mcp folder>/runtime/bin/fernflower.jar.

Open up cmd (or similar), pushd to the folder where your JAR was extracted, and run fernflower folderwithclasses folderforsource.

Use the universal zip, not the sources.

Then use MCP's normal scripts.