Boot Camp problem on MacBook Pro (2015) I installed Windows 10 with Boot Camp Assistant, but when I press the option key on boot, it shows only the Macintosh HD partition. Why is that happening? Is the BOOTCAMP partition not bootable?

Note: I also had a big problem on the past that I solved. I partitioned the SSD 6 times and I lost my OS X partition and Windows partition. Someone helped me and I made the disk single-partition again and found all my files. 

BOOTCAMP partition looks like this:
You have not actually installed Windows. Your image shows the BOOTCAMP partition is MS-DOS (FAT) formatted. If Windows installed, the partition would be NTFS formatted.

At some point during the installation, did you tell Windows to format the BOOTCAMP partition? See step 4 here and "Format the Windows partition" step here. If you skip this step, you will get the following message:



The Boot Camp Assistant creates the partition to install Windows. The format is MS-DOS (FAT) and the label is BOOTCAMP. In the Windows installer, you must reformat this partition. When you do this, the format will be NTFS and the BOOTCAMP label will be removed. If you watch carefully, you will see this happen. After Windows installs, the Boot Camp Support Software is executed. This will rename the Windows partition back to BOOTCAMP. In the above image, you need to click on the "Format" button.