Hey, @NickyGouna. That’s concerning! Let’s figure this out so that you don’t miss out on any sales.
In general, when there is unexpected behaviour on your storefront, like a missing Add to Cart button, it usually has to do with one of the following:
Which theme are you using? Have you edited your code, or added any new third party apps recently?
Please also share your domain name so that I can take a look at it from my end to see if there is a clear indication of why your Add to Cart button is missing; I’ll be better able to guide you in the right direction towards a resolution. Thanks!