Hi Atul,
From which source your feeding data to your cube?
if you have DSO before you info cube then you can directly load whole data from DSO Active table to cube.
if your directly loading data from data source(ECC) to cube then please check whether your psa holds historic data or not.
if not then again need to reload whole data from source. if psa holds historic data then you can reload it from PSA to cube.
is this prod data is copied to qua recently?
about restore , please check with basis. as i think it won't be easy to restore the deleted data.
Thanks