Has your friend accidentally changed languages? That can cause that problem.
Sometimes on the bottom right theres an "EN" symbol for english - can your friend click on that and change it to english (it might be on french)?
If your friend doesn;t have that try this:
Press the left shift button and press the CTRL button.
This should change it back to english characters/layout.
One last thing:
control panel
region and language
keyboards and languages
change keyboards
then remove every other language except for English (us) or whatever region you want to use. before you accept try to double check that ur keyboard is on English before you do this, i had a keyboard error the first time i did it because my keyboard was still on french. (to double check make sure you are getting the proper slash when you push slash, to change it if you're not getting the slash use the (left ctrl + left shift for 3-4 seconds)