What if I dont  have the obc non creamy layer certificate at the time of counselling And I scored enough mark for admission in general category sir ? will they reject me?

You can either opt for non cream layer or for general category.  If you have mentioned in your form that you are from OBC category and you fail to produce the certificate then yes you will not be considered for admission despite scoring more than enough marks required in general category. 

Are you sure about this ? is there no other way 

See you can always talk to to the concerned admission department but so far as the rules of DU admission are concerned they do not allow students to shift category. Having said that the department may relax some of the conditions but you will have to communicate this issue to them. They may relax few conditions given the fact that you have scored good marks and ignore the technicalities. I can only infer from the rules and I will not misguide you therefore request you to communicate with the department also because they may relax the condition and then you can get the allotment.

Thank you Parvesh ..how to contact them.? They are not attending the call and not replying the mail :(