you need to obtain a medical certificate from the surgeon who performed the amputation surgery stating the reason for need of it, with the document please visit district health officer of your permenant address over cnic to endorse the same for your right hand being amputated with exact date.
complete the documentation and write an application to the Senior Supretendent Driving Licence Branch of your city attach your old driving license and the certificates issues by DHO.
He will call upon you and assign a date for driving test if all goes well, your driving license will be re-issued with Orthopedic class C disability which require a passenger present in car. ( so far only 270 people under this class have driving license - some are soldier officers with active service desk jobs )
@HanifBhatti sir if he is in Karachi and you want me to help, you know how to reach me.