Look at this schematic from http://www.eetimes.com/document.asp?doc_id=1274924
http://m.eet.com/media/1064822/maxim_comparator_detect_fig1.jpg
If the detect line is broken then the laptop won't switch. Keeping in mind that most shops will not repair this but replace the main board for many hundreds I suggest you get some USB headphones or this item:
http://www.amazon.com/Syba-SD-CM-UAUD-Adapter-C-Media-Chipset/dp/B001MSS6CS
http://ecx.images-amazon.com/images/I/71X2w2pzsIL._SL1500_.jpg
i tried all the tips and tricks available on internet but it really doesnt help... i removed the driver and also did the factory reset... still there is no difference. please help me out

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