First of all, period date may alter/ delay 1-7 days and cycle may vary from 21-35 days. It is considered as normal thing and occurs mostly due to hormonal imbalance & mental stress.
Here, you need to rule out pregnancy
by doing one blood test
for beta-HCG at the earliest.
Other reasons for delayed period are hormonal imbalance (most common in this context), stress/ anxiety/ mental upset, ovarian cyst
, irregular diet pattern, wt change, thyroid disorder
Consult with your gynecologist for relevant examination & investigation like USG pelvis, complete hormone profile etc
Avoid stress by regular deep breathing, take healthy diet with iron supplements
, keep bowel regular, control body wt by regular exercise/yoga and take proper sleep.
Be well & take care.