Can't work means can't get paid

Help! I'm locked out of my work laptop! Yesterday, I was trying to set up printer sharing on my home network. I plugged my printer into my desktop, and set it up to share (see here and here). I couldn't get it to show up on my laptop, which is still set up for the office network I used to use, even though I no longer go to the office and am now just a weekend telecommuter. So in the process of poking around to get it working, I changed the Network ID. I changed Option 1: "This computer is part of a business network, and I use it to connect to other computers at work." to Option 2: "This computer is for home use and is not part of a business network." However, unlike what the MS support page I linked to says, it did NOT prompt me for a username/password. It just told me to restart the computer, which I did. Now it is not recognizing my password. This is very bad. I cannot get into the laptop at all.

1. Is there any way for me to get back in and change that setting? I don't have the password for 'Administrator' (though my account was originally set up with computer administrator access). I don't have an XP Pro CD. I have a full-time job during the week that will make it difficult to bring the laptop in to the office to be reset by the IT manager.

2. Can anyone help me with the printer sharing? Why was my printer not showing up even when I searched "HOMENETWORK" not "OFFICENETWORK"? Does it have anything to do with the fact my desktop is running XP Home, not Pro?