If you've taken biology as well in your eleventh and twelfth then your eligible to take admission.
You will have to prepare vigorously for the NEET exam as it's highly competitive and then take the exam with utmost seriousness. If you get a good rank you can always pursue medicine.

Hi,

If you are not happy with engineering and always wanted to go for medical, I do not think anything in this world will ever make you happy until you become a doctor. Rather than regretting it, it is the best time to take a step forward.

Get in touch with the nearest higher secondary school and inquire if you can straight away go for biology exam and have a PCB which will allow you to take pre-medical test (if this happens, it will save two years of yours but even if this does not happen do not stop). If you can not directly go for Biology exam, may be you will have to take 11th and 12th standards again. So start a job you like for a period of two years and simultaneously appear for the exams. You will easily be able to do it and later go for pre-medical test.