
To assess the loss under any policy, insurance companies depute surveyors who are qualified professionals like chartered accountants or engineers. Depending on the case, they can devise a method to assess the losses.
In cases like yours, where there are no books of accounts, surveyors can assess losses on the basis of volumetric analysis of the shop such as the shop area and the shelf space utilised for keeping the items. A list can be drawn whereby the quantum of stock that can be stored can be determined. On the basis of this and the present price, the value of the stock can be ascertained.
They can also draw their conclusions on the basis of your transactions recorded in bank statements, sales tax returns, or IT returns, copies of which can be obtained.