my problem is that i changed some compiz configurations and i broke my copy/paste(ctrl-c, ctrl-v... basically all the shortcuts that start with ctrl, including Eclipse's ctrl-space).
i searched for key-shortcuts, i found a whole lot of them besides the ones i need.
does anyone know how can i restore my keys back?

It sounds like compiz could be grabbing your control modifier, try to search through there and remove any compiz effect that only has control as a keyboard shortcut.

thank you for your reply, i solved the problem by deleting compiz's configuration file