No Audio Input/Output Devices detected!

Hi All,

My Mac was functioning wonderful until, I upgraded to yosemite suddenly the audio input/output devices aren't detected! I have tried all the trouble shooting steps online NVRAM, PRAM to clean install of the software back to mountain lion and now running mavericks, but all in vain!

Took it to the authorized service centre they failed to diagnise my problem and detected fault on MLB (Main Logic Board) for which they are charging a bomb!

I would like to know if there is any work around to get the sound working! I read about external audio devices which doesn't require any drivers come in handy (Sabrent) should I settle for this? I am confused and frustrated with my MacBook Pro! Please HELP!

TIA