I would like to display the datagrid row items in textboxes when double clicked on that row. Can anybody please help me with this "simple" problem?

I assume that you mean you would like to put the DataGrid into edit mode.

MSDN has tons of information about this and it is actually not too bad < s >.

Check out this topic in MSDN and follow the links:

Allowing Users to Edit Items in a DataGrid Web Server Control