Why this is happening?

I have my last periods on 13 June and finished on 16 June. Today is 21 July and I have not my periods what is the reason I don't know. My periods were regular and never missed like this type.
Updates
+1 y
I never had sex and I am virgin
Updates
+1 y
I get my periods today after 10 days later
Why this is happening?
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