If you're using Windows. You can restore your system, fortunately. Unfortunately, if your system doesn't make any backups, you can't restore it. Here's the way to restore your system. Start > All Programs > Accessories > System Tools > System Restore Choose 'restore my computer to an earlier time' then click Next, choose a restore point (if you want to cancel everything you done in last week, choose last week date), click Next, and click Next again. Done!

There is nothing you can do other than to look around facebook, and trying to unblock that page, which I think is quite possible.

But you can't undo everything you have done in the past week, because what you have done online is stored in a completely different computer.

Using System Restore and other options like that will only reverse the changes made to your computer, but won't affect the changes you have made to your "online" self.