If you're specifically looking for a PDF related to "Vennello Aadapilla," here are some steps:
For a high-quality printed edition, it is available as a set with other works on Amazon India . Legacy
Start with the resources listed above. And if you remember any more details about the story you're looking for (author name, plot, year), try asking in Telugu literary forums like on Facebook or తెలుగు కథా వేదిక (Telugu Story Forum). Someone there may recognize the title.