To be honest, what you have implied to me was that you had or have no idea what you are doing and edited core files which will mess up the game if there is one mistake. In the event of any stuff ups, you should always back up before you make any changes to any core or config files in Amnesia, because it can be become heavily unstable for both the normal game, custom stories and to some extent Full Conversion mods.
Here is my material.cfg file. Just copy and paste everything from this into your own materials.cfg file, deleting any/all changes you made, and then save. Hopefully that will fix it up.
If you go to re-edit the materials.cfg, just click on it and make a copy. Even that is considered backing up. If you stuff up, just rename the copy to materials.cfg and delete the config with an error.