Why MacBook is not booting?

hi every body, my mac book suddenly stopped switching on, until yesterday it is fine, yesterday i have just closed the lid & left it on, today it completely stopped, i thought the battery drained, & kept for charging for more than 3 hours, battery got fully charged, & green light appeared on the charging cable, but macbook is still the same, no sound,no light, nothing, i tried resetting some power issues like holding power button 5 sec etc, but nothing is working, no light & no sound

please help me, what could be the problem,, im really waiting for answer please helep please, thank you