Take a look at the link below. It might be as simple as Section 2 on the page if you are at root prompt (root@owner-netbook:~# ).
Give it a try. If that doesn't work, do you see a boot menu with one or more options? I expect not as it would likely show the name of the distribution if you did. If you do see some sort of menu, try option 1 on the page below:
For your information, if you are not familiar with Linux and you try the method above, you will not see anything when you enter the password, not even the customary asterisks, so type carefully.
If this doesn't work or you are able to obtain more info on what the OS is, post back.