Man, you have to specify where exactly where collected the shells. if you know where were collected, you can looks for books of marine species of a determined country and region of your country and start to compare pictures.
I agree with Henk that this looks quite like a vanikorid. But there is a similar-looking pyramidellid genus called Phasianema. The latter is sculptured by rows of pits, as commonly seen in shelled "opisthobranchs", whereas vanikorids have the cancellate sculpture typical of caenogastropods.
Faiza Iqbal you should at least thank people for their replies instead of such abrupt responses. Why ask only to then tell people they are wrong. If you don't know, then how do you know other people are incorrect?
Andrew Paul McKenzie Pegman thnks for your concern. I am not giving abrupt responses, It's your way of seeing, I am correcting you that's its not Nerita because Nerita undulata is a common gastropod..