I'm confused....Yesterday things worked, today they don't? Or you are trying something different?
You are trying to burn CD, or DVD?
You have to make sure, your disk, and your burner are compatible.
For instance, if your burner is DVD+RW, you have to have DVD+R disks.
If your burner is DVD-RW, you have to have DVD-R disks.
What burning program are you using?