Recently I've lost my USB dongle. help me out were can I find it to buy or is there any other way to use it.
Welcome to the Dell Community @Vabesh
The only reason to have a "Dongle" is if your laptop does not have bluetooth.
If your laptop does not have bluetooth then you will need to purchase/borrow a dongle.
Computers that have bluetooth should be able to link/pair to most keyboards, mice, headsets, speakers etc
Borrow a dongle; turn off computer; plug in dongle; take battery out of mouse; turn on computer; ........ put battery in mouse, place it near dongle.
Mouse should find dongle, make friend with it, work as intended.
If works, (it did for me) purchase a handful of dongles on ebay.