le of the DVD-RW again, if it’s a laptop, take the DVD-RW off and clean up the ports and then install it back. Otherwise, it might be the DVD-RW hardware problem, probably motherboard problem. Hope this could help you!
3): Under safe mode, operation system doesn’t load any drivers, so it’s normal if system cannot find DVD-RW.  Here we just talk about the latter two, if eliminate virus factor, the DVD-RW volume still couldn’t be found out, then you could follow the next methods:
-Use “Super Rabbit”—“System tools”—“DVD-ROM/CD-ROM repair tool” and repair.
-Enter Control panel, choose “Add new hardware”, and then keep going step by step following the prompt. After system finishes checkup, generally, DVD-ROM/CD-ROM could be found; or enter control panel, and choose “Device manager”, delete the item “Disk controller”, and then restart the computer. As DVD-ROM/CD-ROM uses a same controller with hard drive, so after deleting it and restarting, system would auto recognize them, generally, the DVD-ROM/CD-ROM could be found back.
-If the methods above don’t work, then first boot DVD-ROM/CD-ROM under DOS mode, such as to load omnipotent driver IDE.SYS to solve the problem.