problem with Arduino uno


can anyone figure out, what could be the cause for arduino uno board is showing error in uploading the code, as in these times i had loaded many sketch and all of a sudden its not getting loaded with the code and what could be the problem, is this with hardware or software.
kindly give me any remedy and if any problem is there with hardware, how to diagnose it, and through this forum i found that, there is an issue termed as FUSE, i dont know what it is all about, and is it mandatory to set the fuse , my doubt is this, it worked in all these months and now its behaving like this.

kindly let me know.



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