In order to qualify the NEET test, you need to have Biology as one of the subjects in your science combination apart from Physics and Chemistry. Since you did not go through Biology in your class eleven and twelve, you may not be in a position to write the NEET examination.
The following are the essential condition to be fulfilled prior to appearing NEET test.
1) The minimum age of the aspirant must not be less than 17 years of age while appearing for the test and the maximum limit has been fixed as 25 years. However, a relaxation of five year is allowed for OBC, SC and ST candidates.
2) Minimum scoring of marks is 50 percent along with Physics, Chemistry and Biology combination.
3) The maximum attempt for the said examination is three times and hence one should qualify the test within this prescribed time.
In your case, Biology is not in your combination, you have to reappear in the examination along with Biology and for your further query, you may meet your Principal of your school.