You can type "MENUBAR 1" to revert back to the classic AutoCAD menu structure (the reverse is "MENUBAR 0"), and "RIBBONCLOSE" to shutdown the ribbons.
I hope this helps,
Johannes doesn't sound like an English name and so it maybe worth pointing out that the commands Nuri highlighted would likely only work on an English version. Any language version of AutoCAD will accept English commands if it is prefixed by a character, unfortunately I can't remember what this character is....that said it is probably something like a ' or _
Sorry I can't be of more help than this but its been a long time since I worked on a non-English AutoCAD.