I've been taking the pill for 4 years without a period. Now my period has come back. Is this normal?

Its not normal to have no period for 4 years.

"There are birth control pill regimens designed to prevent bleeding for three months at a time or for as long as a year. But it's possible to prevent your period with continuous use of any birth control pill. This means skipping the placebo pills and starting right away on a new pack.May 4, 2016"

Talk to your ob-gyn.