Well H I personally get all my data backed up onto an external or something first.
If they didn't give you a disk (CD) then they might ahve set it up like a lot of factory jobs and they set up a partition that you do what is known asa factory default - power on and tap a certain F key what ever they say it is.
Now that is for the situation where you might have to reinstall.
Now how about you disable the security for the time it takes for you to try that
KB 947821 see what happens. Just as a matter of curiosity what is your security because some can be really quite pedantic.