MacBook Air not connecting to WiFi router Digisol DG-BG4011N

I am facing a perplexing issue with my MacBook Air after it stopped connecting to my ADSL wireless broadband router(of the make Digisol's DG-BG4011N). Infact, I had bought this router newly 3 days back and had successfully configured it such that the MacBook Air was connecting to it.

However, from yesterday onwards after I switched on both, MacBook Air has stopped recognising the WiFi network of my router. It is recognising all the other networks in the neighbourhood except this.

There is no issue with my WiFi router as my other devices are successfully connecting to this router.

Any light thrown on how to resolve this issue will be highly appreciated.

Thanks