Booting from an external MacOS(X) disk and using Disk Utility / First Aid might help. It seems that sometimes when a Mac is booted from Windows or Linux, some part of the MacOS(X) boot block gets altered, which then prevents booting from OSX.
Make sure you have a full backup of your hard disk before trying anything else. Then google "osx boot block gpt" to learn more about the boot block and GPT, and how it might be possible to fix it (in case the First Aid did not lead to the desired result).
No first aid and i cannot bot to the windows but i "read about osx boot blockgp" for my mac is only black screen no sound, no usb, but when they run bt keyboard run to ....