Android 4.3: no external memory available? Mount extSdCard?

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http://stackoverflow.com – I have this problem,, which occured while using CM10.1 for a while. It just happend after a month or so. My exterdan Micro Sd-card 16GB was unable to reached out to which I mentioned when trying to access Gallery. I can't even save media send by Whatsapp or take pictures. In Settings > Storage Settings i mentioned that Android is showing me the SD-card and is able to calculate total storage of this SD-card. So tthis is telling me that the SD-card is working in Android but not able to use it somehow. I have checked if it is working on my PC (yes it is) I have already formatted the SD-card i (HowTos)