Because of this: http://www.gamesas.com/index.php?/topic/1093567-radio-stutter/
i wanted to edit the "Existing 2.0" radio station mod so that I plays .wav files instead of MP3s, I did probably something wrong in the process because it completely! stopped working after my changes

Heres what I did:
GECK / Data / select mod.esp

linked the new wave files in this section (see screen)
http://img405.imageshack.us/img405/2003/existence21.jpg

saved this as modx.esp, load it alone "and" right past the old mod.esp.
in both cases the modx doesnt do anything at all.

Wheres my fault, i'm not that experienced with GECK ^^

thx in advance

Are you saying you tried to 'mod' a 'mod', or you simply edited the existing mod?

You can't mod a mod, just to be clear. (without a lot more work involved.)

I did exactly what I wrote above, whatever you call it.

I did exactly what I wrote above, whatever you call it.
Modifying, Editing , what is the difference?

Pretty standard problem, you ran into the Mod Isolation thing. You'll need to read up on mod de-isolation on the http://geck.gamesas.com/.

I cant find anything regarding isolation or de-iso, can you link the site directly ?

As I said you "cannot" mod a mod. That is making a new ESP (plugin file) mod file based on another ESP mod file. You can only mod an ESM file, (Master file).

If you are editing the ESP file and NOT making a new file name, then there should be no issues. If your making a new ESP file with the other ESP file active, then that will not work. That is why I was asking WHAT you are doing.

I made the changes to Existence2.0.esp(239kB) , saved it as Existence2.1.esp(11kB)
What exactly happens when I load them both?

How can I just edit it, just overwrite it?

When loading the GECK, set the mod you want to edit as the active file, this way your changes will be made inside that file and not save a new one.

Hm did that but the radio doesnt seem to like my wave files
No music playback, just the dj voice

They need to be something like 44100Hz... Bleh, duno much about audio...

They do.