I don't even think the Acer Aspire One (d25-1958)
has Linux on it. I think it's Windows XP. There is an Acer Aspire One
that comes with Linux, however, but I don't think the d25-1958 does.
The Acer Aspire One with Linux uses Linpus Linux Lite. I checked the Linpus website, and found this information
Originally Posted by FAQ from Linpus site
How can I reset the password? You will only need to use your password if you are going to use the command line and add programs. The default is 111111. Go to Settings and press Password; enter the default password and follow the instructions.
If you're actually using Windows XP and not Linux, then it might be wise to look elsewhere for assistance. You're best bet either way is to contact the manufacturer (Acer) or the store you or your parents bought it from.