Zara,
Losing weight can be caused by a myriad of issues....behavioral (too hot to eat), other cats that are annoying this cat, dental disease, organ dysfunction as well as internal parasites. You state that you are residing in Islamabad. I am not fully aware of all the types of parasites that your cat might be exposed to but keeping your cat on a good schedule of deworming is an excellent idea as well as keeping the cat indoors. Hair loss can be due to allergic skin conditions, external parasites (some cats are so sensitive that a single flea can cause excessive itching and hair loss), and internal diseases. I would recommend that you get your cat to your veterinarian at your earliest convenience for a thorough exam, possible skin scrapes and/or fungal testing and possibly a general blood and urine test to rule out internal disorders.
Best of luck....
Dr. Bernadine
thank you so much doctor Bernadine, your advice was of great help to me..i am also grateful to you for your time and assistance..God Bless You