What would happen if I don't have a published research paper during my education? I am a 3rd year Ph.D. student. My field is computer science. I've worked on my topic for a long time, but finally, I found out that there are a lot of parameters correlated with publishing a paper. So I don't have hope for publishing a paper, since I should do it all on my own. What should I do now?
Apply to lower level journals (not conferences, avoids the issue of travel).  Just do some solid basic work to get your confidence up.  Not "home runs" or "triples" but singles or bunts.  Anything other than a strikeout.  

Story:  I had a girlfriend who was hired to sell huge enterprise level deals for a packaging company (not software, the boxes, but also box systems, services, etc.)  She was hating life because she hadn't sold anything and didn't feel she was getting support to sell these huge deals and all the other salesmen would drop a price list and make little sales (not systems).  I advised her to (counterintiutively) go ahead and sell some simple stuff like the Cro Magnon salesmen had advised her.  The problem was that she basically had ZERO for a score and hadn't even learned how to use the systems (order entry to cash, credit checks for new customers, etc.)  And her confidence was in the dumpster.  She took my advice, felt WAY better after making a little sale and eventually got one enterprise deal done.  

You need to get your confidence up.  Just go to some decent journal.  Not a fly by night predatory thing.  But second tier decent, looking for datapoint papers.  And don't try to claim you've invented hydrogen. Simple, simple, simple.  And short ("least publishable unit").

P.s. When asking questions here, it helps if you tell us the field.  There are huge differences by field.  It's good if we/you can generalize as well (not requiring answers to be field specific), but if you give us the field as well, you will get some targeted answers from practitioners.  I'm assuming it is computer science based on "stack exchange" and the comment about conferences, and I am not as familiar with that field, but many others here are.