Refer the below link and on gridview row click make ajax call to get the Long & Lat for that selected row and pass the Long Lat to the OpenLayers.Geometry.Point(Long,Lat).

http://stackoverflow.com/questions/26138416/import-sql-data-into-js-array

Refer the below link to call the gridview row click event.

Delete Row from GridView and Database using jQuery in ASP.Net