just a couple of questions, why did you initially re-install? Also does the install keep sticking on the services start up screen? If it's only frozen the once then you might be ok and I'd just reboot. Lastly could you post your lappies specs please.
Use your installation disc and find Command Prompt. Then run these commands:
Diskpart List disk Select disk n(where n is the number that was given for the disk where you want to install) Clean Create partition primary Active Exit
Note: This will clean the whole disk and allocate one partition into which you can install. Since your niece deleted everything, I assume there is nothing to be saved. But if you need to save anything, post back.