I'm not sure if you have to mount the drive first. Read
and
to get more information about how you create iso files and burn data on disks. Usually the GUI burning tools are merely front-ends to these apps (and others).
I still must say: a reinstall is often not needed. It would teach you so much more to find out how to solve the problems rather than just reinstall. Reinstalling the OS is something Windows users do; in the real world, you fix the problems. And next time you know how to avoid them (if you don't fix them, you don't know what happened and will probably do it again).