Linux – Cannot dual boot Windows 7 after installing Linux Mint

The /dev/sda is your disk. /dev/sda[number] are partitions. One of them is Windows loader, one is your C/, another are D:/ and E:/. I don't know what is additional one. Which is which you must check by yourself.

I think you don't fully understand what do you should do, so there is simple instruction:

1. Delete E:/ (I think it's empty)
2. At the end of earned space (it should be end of disk space) make new partition with 200 MB of space, ext4 format and select /boot mount point. There will be installed GRUB.
3. Create next partition with freed space. It can be at begin or end space (). Partition must be 10 GB or more, but best way is 16-20 GB (IMO), select / mount point and ext4 format. This will be Linux system partition.
4. Create another one partition. Select ext4 and /home. There will be /home catalog and user files. Set it as big as you need for files you use on Linux. If you don't create it, /home will be at system partition, what is not good solution.

If you have some additional space, make there partition with ntfs format and without mount point for files you would to use form both systems. However in my opinion, better way is to copy data from D:/ somewhere, delete that partition and make bigger ntfs one for files with access form both systems. In this case / partition must be at the end of free space, just before /boot. Then you should have:

1. about 100 MB ntfs for Windows loader
2. 48 GB ntfs for Windows
3. ntfs partition for files accessible from both systems
4. ext4 partition for files accessible from Linux
5. 10-20 GB for Linux
6. 200 MB ext4 for GRUB In this order.

//Sorry for my English.