hey guys, i just got a macbook pro. it came with no OS so i installed Yosemite version 10.10.2. the thing is the macbook has not sound at all. no output device, i use the search tool here to look for something similar but i came with nothing, I've seen some solutions like erase some files, clear memory, etc but i don't hace the files that are mentioned and I've erase the memory a lot of times, i wonder if its maybe a physical problem with the audio card or something because nothing make sense anymore. here is a shot of what my audio settings looks like, no output device, sound lock. let me know what you think thank you!