Hi Sakshi,

According to the official website,it clearly states that you can give JEE Advanced in the year when you gave your qualifying exam i.e 12th Boards and the year following that. It does'nt matter if you gave JEE Advanced in 12th or not,all it matters is the year of your 12th and following that year. So sccording to this,I am sorry to say but you cannot give JEE Advanced now. You surely can give MAINS and many more exams. You can try for them,but I would surely not advise doing that. 

Best wishes!