Notepad isnt working on windows 7 for scripting (i think its about java)?

Ok, I write scrips and I use the notepad software a lot on my laptop but now when I save the files to my desktop the show up with a question make in the icon for the file. When I try to open it an error pops up and says I do not have the correct software to open it. I save my files as a .java (like woodcutter.java) and i script for runescape bots but now I can save them and use them. plz help!