Thank you, toleda. Unfortunately, I don't know even how to actually check for or create the two requirements (i.e. have or restore native AppleHDA.kext using OS X combo update, and make sure Realtek ALC Injection is installed). I suppose I should never have built a hackintosh with my limited skills and knowledge; using the tools and instructions provided at 'tonymacx86' worked for me but didn't equip me with any understanding of what I was doing... I am resigned to live without sound - and thanks for trying to help anyway!
My Hackintosh runs on a Gigabyte GA-Z77X-UD5H with the ALC 898 codec and had normal sound until some time recently. I hope somebody can help me to get it back, but please be mindful that I am not very technically savvy and probably need somewhat detailed instructions of what to do if there is a solution. The hardware system report only lists two devices for Audio (see below) even though two ALTEC Lansing speakers are hooked up to it (which play normally in Windows 8, which is on another disk and boots from that): AirPlay: Default Output Device: Yes Manufacturer: Apple Inc. Output Channels: 2 Current SampleRate: 44100 Transport: AirPlay AirParrot: Default Input Device: Yes Default System Output Device: Yes Input Channels: 2 Manufacturer: squirrels Output Channels: 2 Current SampleRate: 44100 Transport: Unknown