Dropped MacBook, lots of disk io errors. How to fix?
Sounds like your harddisk is busted.  There is a feature in MacBooks which is there to help protect the disk by parking the head in the event of a fall but it's not foolproof.  Even if you managed to resolve the errors, I wouldn't trust that the disk had not been damaged and you just risk further data loss in future.  Best thing you can do is backup anything you can salvage if you don't already have a backup while the disk can still operate and either have Apple or an authorized repair centre replace the harddisk.  You can also replace the disk yourself if you feel capable.  There are instructions in the manual and also on the Apple support pages.  You haven't said which model of 2011 MacBook you have but here are the instructions for the 13-inch (page 37)  

http://manuals.info.apple.com/en_US/macbook_pro_13inch_early2011.pdf