try this. follow the same steps to either open a terminal from your black screen (ctrl-alt T) or switch to a new console (ctrl-alt F1) then type the following to reset compiz
gconftool-2 -recursive-unset /apps/compiz-1 unity --reset
if that does not work try
cd ~; rm -rf .gnome .gnome2 .gconf .metacity .compiz-1 .config/compiz-1 .config/dconf
either of those steps should reset compiz to default settings.
try this. follow the same steps to either open a terminal from your black screen (ctrl-alt T) or switch to a new console (ctrl-alt F1) then type the following to reset compiz
gconftool-2 -recursive-unset /apps/compiz-1
unity --reset
if that does not work try
cd ~; rm -rf .gnome .gnome2 .gconf .metacity .compiz-1 .config/compiz-1 .config/dconf
either of those steps should reset compiz to default settings.