You have scored less in the subjects Chemistry,Boatany, Zoology od B.Sc II year. In general we would need at leat 50% marks in graduation degree courses to move to the next year.
Delhi university allows students to take up their third year course (http://dubeat.com/2013/07/students-who-failed-1st-2nd-year-exams-can-move-to-next-semester-du/), while preparing and appearing in the suppermentary exams along with the next freshers for the second year subjects. In your case, you need to appear for the supplementary exams and clear off the pending subjects, so that you can focus on your third year studies and exams.
You can find out other students who are in the similar state as yourself and then as a group request for extra classes or help from the teachers and even the good students of your own batch.
You can consider focussing on the practicals and the internals well so that your overall score improves. You need to study hard with time given for the sections that you are weak in, the subjects that need more attention,refresher notes, old question papers, mock exams etc.
Once you put in your sincere efforts then you would do well.
Please check this site for the back or supplementary exams and apply online (http://rmlauexams.in/)
Failing in subjects does not mean the end of the line or education. Now, instead of feeling sad, you need to analyse the reasons for your poor performance. Was it lack of preparation, lack of effort, unable to understand the subject etc.
I would suggest, you to sit with your favourite lecturer or teacer in Physics, Botany and Zoology and find out your strengths and weakness. Once you do this then you would have identified the areas where in you need more focus or attention.
Some students who are unable to study well for personal reasons or social reasons plan to take a break and drop a year. I would suggest, make an honest assessment of your subject knowledge, the time in hand before the supplementary exams, give the exams and then consider the next course of action.
There are some online sites that give you notes and course material for B Sc second year subject wise, you can check it.