Hey Shivam, 

If you haven't got your obc category rank because of not uploading obc certificate then you can e-mail your obc certificate to iit roorkee this year. Give a proper justification why you couldn't upload your obc certificate on right time. They will consider your request and will provide your category rank but do it immediately because it can take a couple of days to get a reply from iit roorkee. Last year one of my friend wasn't able to upload his obc certificate on time but he mailed his obc certificate to IIT KANPUR(last year's organiser of jee advanced ) in between the counselling period and he got his obc category rank before the end of the choice filling. Do you must do it immediately before choice filling ends. 

Best of luck!