If I'm understanding you correctly, you have tried writing a CD-R since you had this CD-RW problem, and it's OK.
If so, there's only two explanations. One is that your CD-RW media is bad, the other is that the drive itself has failed. The way to tell will be trying different CD-RW media (ideally at least a different batch if not a different brand). If you can successfully write a CD-R, it suggests the CD-RW media is bad. If you can't successfully write a CD-R, it suggests the drive is bad.
If Nero can write a CD-R OK on the drive subsequent to the CD-RW problem happening, it's highly unlikely to be a software problem.