can't get Malayalam language on my phone

Welcome to the forums fasli. There are a couple of apps in the Play Store that might help you out. fontomizer will let you install south indian regional fonts so you can read them; then install MultiLing keyboard to be able to type them. I got this info from Sam Alexander who is the owner and author of DailyTeck.com. Sam lives in Kerala and wrote an article about this very issue last year.