While using dual boot system (Windows + Ubuntu) there can be problems with mounting the drives of Windows inside Ubuntu. This problem generally occurs with Windows 8 and above versions.
When we shutdown our system it does not fully shutdown in case of windows 8 and above Os, It actually hibernates and when we turn on the system again, it reloads the initial system state which is called Hybrid Boot which speeds up the startup process. Due to this linux systems are not able to mount the windows drives. To fix this problem we have to disable the hybrid boot in the Windows system which is also known as Fast Startup. After disabling the hybrid boot your system take some time to load on Startup usually as Windows 7 takes and will solve your mounting problem with Ubuntu.