What's the difference between  everyday, daily  and  regularly ?

there is no difference in meaning between daily and every day. It's just that daily tends to be used in more official or commercial contexts. daily = done as a matter of fixed routine, on a regular basis each day.
every day = more of a statement of fact to describe when something is done. And, regularly does not exactly mean daily or everyday because regularly just means a constant frequency or habbit. For ex. when people say that they visit the dentist regularly, it doesn't have to mean that they meet a dentist everyday, it can also mean that they visit a dentist frequently,like once or twice a week.

Hope it answered your question...

:)