Can I do LLB after completing B.A course??? What are the good colleges for this course???

Yes, you can do LLB after completing B.A course. You need to appear in the Law entrance examination. You need to appear in one of the following entrance examination:

Kerala Law Entrance Examination,
NLU Delhi Exam,
NALSAR Entrance Test,
Common Law Admission Test (CLAT), etc.

Following are some top colleges here you can apply to pursue this course:

National Law School of India University, Bangalore
NALSAR University of Law, Hyderabad
National Law Institute University, Bhopal
West Bengal National University of Juridical Sciences, Kolkata
National Law University, Jodhpur
Hidayatullah National Law University, Raipur
Gujarat National Law University, Gandhinagar
Dr. Ram Manohar Lohiya National Law University, Lucknow
Rajiv Gandhi National University of Law, Patiala
Chanakya National Law University, Patna
National University of Advanced Legal Studies, Kochi
National Law University, Orissa
National University of Study & Research in Law, Ranchi
National Law University & Judicial Academy, Assam.