First thing which you need to do if you lose all your fonts is to check list of official original Windows XP fonts. You can see the list on Windows XP Microsoft web-page here : https://www.microsoft.com/typography/fonts/winxp.htm

When you see the list download all of those fonts (you have them all around the internet for free) and save them inside of one folder on your Desktop. Installing fonts which you download is a pretty simple thing and you can made it just by copying font files in fonts folder. If you never did that before then I advice you to check tutorial where is step by step described how to install new and old fonts : http://pc-problem-solutions.blogspot.com/2013/10/install-new-fonts-on-your-windows-xp.html