ما هي أسباب نشأة المخزون السلعي الراكد؟ وما هي خطة التصرف بالمخزون السلعي الراكد؟

Could be a combination of some or all the following; 1.
A Sudden decrease in demand 2.
A dispropotionate increase in supply without creating the necessary demand to cycle out. 
3.
Competition, even if indirectly could divert consumers to another product. 
4.
High prices, which could also divert consumers away from the product in store.
  Best strategy, should this case arise, is to lower prices significantly.
I agree that at some cases huge losses could be the result, but I believe that no matter how the significant the loss is, it would definitely be better than what the probable losses would be should the stores not be emptied out in time. 
The second strategy is to expose the goods, make sure that product is exposed to the market.
This could increase the chance of meeting an interested customer/supplier to purchase and buy up the supply.