1
My sister told me she could not find the D drive in her laptop any more. I felt strange: how could it happen, since all other partitions of the hard drive were visible? So I asked her to restart the laptop, check disk errors. Unfortunately, nothing worked. Guided her to look at the computer management tool, the partition was still there but Windows 7 thought it was unallocated.
After a long-time running, your computer may generate lots of junk files, like caches and random access memory (RAM), which makes it harder for operating system to locate needed files. However, rebooting may clear all or a part of such files so as to speed up your computer.
C drive is missing in Windows 7