Let me take a moment to thank you for posting on the HP Support Forums.
I understand from your post that you need the wireless dongle for your wireless HP keyboard and mouse. I'll certainly provide you the information for this.
Let me inform you that it is always better to buy the whole wireless kit (wireless keyboard and the mouse with their unique USB receiver). The reason being is because the wireless keyboard and mouse are synced with the USB receiver and changing only the USB receiver may not make either the keyboard or the mouse or both to work.
Therefore, when a situation arises where either an in warranty wireless keyboard/mouse or the USB receiver stops working, we at HP replace the entire wireless kit. You may order the wireless kit online via HP Shopping website or call 1-(800)-180-1810 or 1-(800)-108-4747.
You could also use the HP Store locator web page to locate a store in Bangalore.
I hope this information helps. Please feel free to let me know if you have any questions. Good luck! 🙂