unitless drawing

I got a drawing set drawn as unit less i want get measurements in meters how can i do it ....what is the advantage of "unit less" drawing......and how to turn on all layers at once........also explain how to group existing layers for various categorizes

In AutoCAD, all drawings are unitless for the most part. If you draw something one unit long, that unit can be an inch, a meter, a mile, a light year, whatever. It gets a little more defined when you move into vertical products.

To turn all layers on, type in -layer, then ON, then *, then twice. You might have to repeat to "thaw" frozen layers. You can easily make this into a menu macro or lisp statement for quick execution.