I have a 24v/2oA SMPS (input 230v ac) I want 48v/10A as output.How it is possible?

 

Sell it and buy a 48V/10A SMPS.

 

Or buy a second 24V/20A SMPS and wire the two in series (on the condition that the supply outputs are floating).
The bonus is you now have a 48V/20A supply.

 

Do you have a circuit diagram of the supply you can post?

 

unless you have the circuit diagram its going to be a bit difficult to modify it, the output would probably squeeze to 35v at best..

 

You will also need new magnetics components and all new output components (rectifiers/filter caps, etc) since they won't be rated high enough for double output voltage.