I was trying to convert a roadnetwork table.Its geometry contains both MULTILINESTRING and LINESTRING.I converted all the MULTILINE string to Linestring using the query

update all_india_merge set the_geom=ST_GeometryN(the_geom,1) where astext(the_geom) <> 'LINESTRING';

After conversion Some data has been lost.How can I recover those geometries. Please Help me.