No
It's not possible, I did a system update - formatting the system doesn't remove the updates just all userdata.
You can't undo it.
Yes, depending on your current version of Minecraft, you can update it to completely start on a new slate (deletes all modifications). Or, you can open the minecraft.jar file using Winrar and manually undo what you replace. Or even un-install minecraft and re-install it using your previous licence.
You can't.
yes
reload the window :)
There's no way to undo it, as the update overwrites the old firmware. There's no real reason to remove an update as the updates add new features and increase performance, as well as allowing access to the eStore.
It's currently not possible to undo a quest in RuneScape.
I doubt it. Maybe if you reboot the system, otherwise no.
VERY! what ever you did undo it
go int system settings and select updates catogory
No, reversing time to undo past events is not possible according to current scientific understanding.