Hello,

If you haven't studied then ask notes from your friends. If you are still not getting then you can go for Lecturenotes.in .There you can get all kind of notes. You can get videos from YouTube for any specific chapter or concept if you want understand. For more clearance in concepts and basics you can also watch videos given at NPTEL Site. NPTEL is a online platform where all IIT colleges upload their videos and materials and assignments to help students learn the concepts.

Hope it helps!