Which Graphics card do you have?
Is ubuntu prompting you to install any restricted drivers? If yes, install them.
EDIT: If not check again by running jockey-gtk. Activate your graphics driver there.
unity --reset is specific to compiz:
--reset Reset the unity profile in compiz and restart it.
So if you are just using unity 2d, then try resetting the profile by deleting the configuration file, but I only found how to reset all configurations for your user:
Can I reset Unity 2D?
But I think that you do not have to reset it all, just try:
dconf reset -f /desktop/unity/
I couldn't find any other unity entries in dconf. If it doesn't solve your problem, use dconf-editor to find any other entries in there.
I have also found some unity-2d related settings in gconf under
/desktop/unity-2d. I do not know how to reset these though, so post my value, which should be default as I am not using unity:
You haven't specified why you want to reset unity, but these gconf settings will only reset the favourite icons on the unity launcher and make unity hide when it is not active and trigger something on the super (windows) key.