Greetings to you,

Since you did not appear for JEE Advanced along with your class 12th, you now have only one chance left to appear for JEE Advanced. In order to do so, you must clear JEE Mains in your respective category to be considered eligible for JEE Advanced. Also, the canidadate must have atleast 75% in aggregate (PCM) for general/OBC-NCL category and 65% for SC/ST candidates. Good luck. 

Dear Reader,

As you missed one attempt of JEE main and you passed your 12th this year. So you are left with only one year of attempt (2 attempts per year) of JEE main and you will not be able to appear for JEE advanced because that needs to be attempted only after 1 year of passing 12th. So go for JEE main next year 

Hello friend, i am very sorry to tell you that the only way to secure a seat in Indian Institute Of Technology(IIT) is through not only appearing but clearing and securing good rank in both JEE mains and Advance. As you have mentioned that you have not given JEE so you do not have any chances to get a seat in IIT's.