can't find lg g4 when connected to pc

I simply do not get any pop up on my pc or my G4 . This used to work , now nothing. I am using the supplied cable from lg ( and have tested it with another phone - all ok so i know the cable and my pc haven't had any settings changed ). My phone does charge and my pc does give make the pop up noise . I also cannot find anything on my phone to allow connection.

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