My iPod touch keeps quitting out of the permanent apps and don't know how to fix?

A few days ago my iPod started quitting out of permanent apps that you can't delete off your iPod touch, such as Safari, Youtube, etc. I press on the app, it goes to it for a second, freezes, then reverts back to the home screen. If I doubletap the home button I can play music, but picking songs by pressing the app only works some of the time. Safari does not work at all. So I've looked around the internet and the general consensus is to restore my iPod, but unfortunately a bunch of the songs on my iPod are not in my computers library, so when I sync after restoring, they won't come back. How do I transfer the songs from my iPod to itunes. I have a hp desktop with windows 7. Also, will I lose data from my apps, such as one that stores pictures will I not get them back after I restore? Can I back everything up?