the same thing happened to me and this what i did. First have someone call you (you can still recieve calls!) but dont answer it, then you will get a "missed call" notification in your status bar. drop the status bar and click it. then it will bring you to your call log, but the tabs on the top of the screen labled "Phone, Call Log, Contacts, and favorites" will be there. click on the contacts tab. you wont have any contacts (due to the factory reset) but just press menu and then press "accounts" an log in to your gmail account.
then find a launcher app (any launcer will do) and download it to your computer. Then send an email to your gmail account with the launcher attached to it. An email notification will show in your notification bar. Open the notification bar and click it. It will bring you to the email with the attachment. Next to the attachment will be a button that says "install". press that and wait for it to fetch the attachment (you might want to be cnnected to wifi to speed things up if you can figure that out) then it will pop up with the launcher and just press install again. after it is installed press the home button and it should bring you to your new home
there is alot of steps to the process but it works and i know how hard LGNPST can be for a noob to use...this will get you up and running every time no problem, and i would say its an extremely noob friendly method. (you might want to look into flashing a custom recovery just in case of emergencies like these)