Can not type à , ê , è anymore

What could have happened is that you pressed the keystroke to change the keyboard layout (most likely not on purpose). That keystroke is CTRL + SHIFT. Pressing it again will basically tell windows to switch to the next "keyboard layout" in the list of your computer.

When you install Windows vista, 7 or 8 with french canada, Windows by default will also install the layout for US qwerty based keyboards. So when you press that combination, Windows is switching to the US layout, hence why you lose your accents.

A quick fix to this problem is to press CTRL + SHIFT again to gain access to the other keyboard layout, which is most likely french canada in your case.

You could also fix the issue by deleting any keyboard layout aside of french canada (assuming you use nothing else). By doing so, even if you press that combination accidentally, it won't switch to anything else because the only thing that it sees is french canada.

TL;DR: I needed to re-install my preferred language (in Windows 10, but I don't think it's much different in Windows 7).

In my case, I had ENG and NLD (Dutch). I couldn't use accents anymore either.  á became 'a, etc.  My solution that worked was as follows: press the Windows button and search for "settings" and open them. Search for "language" and click it ("Language Settings", "Region and Language", or whatever looks most promising). Then, click your language (in your case French-Canadian) and click "remove". Then click "Add a preferred language" and find your language again and install it. In my case it worked again after these steps.

Also, during this process I noticed that pressing Windows button+spacebar changed from ENG to NLD (which used to be Ctrl+Shift, I believe).  Could be a Windows 10 thing, not sure.