|Are you wanting to go back to IE8 or is it just that you want some form of IE working?|
If you just want IE to work, have you tried downloading IE9 from here?:
It might well accept it and overwrite what you already have. You need to select the right version for your system.
Alternatively if you uninstall IE9 it should go back to IE8.
Always pop back and let us know the outcome - thanks