Actually, I´m afraid you´ll have to reformat the disc, and unfortunately, it´s not sufficient with "surface" formatting, you´ll have to do a "deep" formatting. And that can only be done on a pc...
And it´s normally quite impossible to regain your data...
We had those problems with our JAZ discs a couple of years ago, and had to stop using them because of all the deaths. (We bought about 100 of them , to let our students keep their material on, but after about a year, 50% of them were non-functioning. The discs... not the students...!:-)
The reason for dying, we were told by the supporting firm, is that the discs are not sturdy enough to allow working on files that are stored on the disc, you have to move them to your comp;s HD, work, and then put them back again. And, that the disc´s "pick-up arm" might scratch the surface of the disc when it´s continually revving (!)