Feel free to PM me if this doesn't work for you and I'll update as we go. I have also created a video showing how to make the changes, you can view the video here. This was done with the Japanese version of windows 8, but the same steps should apply regardless of what language version you have.
Start in your control panel, click here
As you can see, the 2nd language down is English. If the English is not showing up like it is here, click where the arrow is pointing to add a new language, scroll to English and add it.
Next, inside the English option box, click on the options link here
Click where the arrow is pointing to make English the OS primary language
You will need to log out and back in now.
PM me and let me know if this works for you, good luck!