Do you have Preloader installed?
If you do:
Go to the homebrew channel through Preloader. If the screen is upside down, try to bare with it. You're going to need to get an application called Firmware Updater v4.2, by Waninkoko. Boot the application in the homebrew channel. When it starts, follow all the prompts on the screen. When it is done installing (it might take a long long time), your Wii should be fixed. What this does is update your firmware to the latest one. It installs only the essential things, like shop channel, system menu, and IOS. Also it's basically installing a brand new shop channel, system menu, and IOS so your Wii will be fixed.
If not:
I recommend a handy device called a SaveMii. You are also going to need a legit Wii game with later update data on it.
Here is the link to the SaveMii:
http://www.ozmodchips.com/savemii-wii-unbr...mp;currency=USD
Read the product description on that page to see exactly what it does and why you need a legit Wii disc with later update data on it.
I hope I was of some help, and good luck unbricking your Wii!
~Snacks