first  do schmidt reaction that will convert CHO to CN....it will not affect the ketone.....

 

then use meerwein-pondorf-verley reduction..... that will reduce C=O  to CH--OH........ it will not affect the CN group........

 

then hydrolyse and convert CN to COOH..... then convert to COCl.... then do rosenmund reduction to get back the aldehyde group........

 

reagents for the reactions are.....

 

schmidt reaction-->hydrazoic acid(HN₃)+conc H₂SO₄

 

meerwein pondorf verley reduction---->aluminium iso propoxide

 

rosenmund reduction----->H₂/palldium/BaSO₄/quinoline

 

please tell me if there is any error in my steps......