[Anonymouse]

Let me guess: there's only the one account on the laptop?

It's very very easy to prevent him changing anything significant: create a user account for him - and, indeed, for anyone who has access to the laptop. Leave one, and only one, account with administrator privileges; the only person who should know the password for it is whoever's most technically-minded - in this case, I'm guessing it'd be you. If you don't already know how to do it, there are complete instructions here - or you could of course ask Windows Help.

Doing this will also safeguard the laptop against viruses, trojans and the like, because they can't install themselves via a user account. Never browse the Internet, even on trusted sites, using an admin account, unless it's absolutely necessary. In fact, I can't think why it would be unless you're installing software via the Internet...which I wouldn't recommend anyway. Far better to download the software and do an offline installation.

/OT

What make is the laptop? There's probably a recovery partition; this can be invoked with a keystroke during the boot process, though which key is used depends on the manufacturer. You might have a problem if the recovery partition was installed in French as well, but there should be some way of doing it. I suppose the best bet would be to contact the manufacturer and ask their tech support for advice. Or try here - someone on the Annoyances site will know, surely.