Q: sound does not work in win 7 and win 8  in macbook pro mid 2012 13 inch

Right click the speaker icon and choose 'playback devices'. What options do you see?

If you see a faint read light in the headphone jack, the Digital output microswitch is stuck. Do you see an option for Internal speakers in Sound Preferences?

You may want to try a SMC reset - Resetting the System Management Controller (SMC) on your Mac - Apple Support and test. Did you check for the red light?

Uninstall the Windows sound devices and delete the sound devices from Windows Device Manager. Run SMC Reset. Re-install BC drivers for your specific Mac from System requirements to install Windows on your Mac via Boot Camp - Apple Support and Boot Camp: Install or repair Boot Camp drivers.

Please also see no sound using bootcamp with windows 10 and yosemite. Even though this is related to Windows 10, the underlying issue is the same.

Yes. The SMC Reset will reset the Optical port. The drivers should initialize the combined Analog/Optical port. Before you plug in headset, if you see a red light, the problem will continue. Test in Windows for Internal speakers, before you plug in your headset.