How to repair Windows 7 in safe mode with bootcamp? My Optical Disc drive is not working. My windows login screen goes black after selecting windows partition by clicking alt

1. What year/model is your Mac?

2. If it has an external power adapter, does your Mac behave the same way with the adapter plugged in and without it?

3. If you touch any keys on the keyboard, does the screen come back?

4. Is there just a single account on the Windows login?

If the brightness is too low, assume you are at the password prompt, enter your password, and press enter. Does your screen come up normally?

Let us try the simple solution. Shutdown your Mac, disconnect the power adapter, reconnect the power adapter, power up and use Alt/Option to select Windows. Do you see a proper login screen?

Do you have an external Optical drive?

If you do not, you can download an ISO from http://www.microsoft.com/en-us/software-recovery using your product key and create a USB with https://rufus.akeo.ie/ or https://technet.microsoft.com/en-us/library/jj200124.aspx and try a Windows startup repair.