"Also, in that struct there are two collumns as "field" and "value"."
You wrote that the structure is 1x1, so it cannot have "two collumns". Most likely you are getting mixed up by how the workspace / variable viewer displays structures, which by default shows the fields as columns (i.e. nothing to do with the structure size). Rather than rely on a contradictory explanation it would be much more reliable to have the original data to work with.
"When I try, struct(n) Matlab gives me following error"
Of course: if a structure only has one element, what do you expect to get when you try to access its non-existent 2nd element? The same applies for any other array type, not just structure arrays.
