Hello. I want to ask why my server ranking has reseted, i mean why it bumped up from 4,500 position to over 10 thousand. Please reply ASAP.
Is it possible to return to previous ranking?

You probably clicked the derank button, then reranked it later.

No it is not possible to undo that.

The is no way i click this button

So if DERANK was clicked after i click RERANK after a week previous ranking would return. Is it true?

Correct - it would take about a week for rank to return.

Where is this button?

The button you originally clicked was "DERANK SERVER". Shortly thereafter, you would have clicked the "RERANK SERVER" button that was in the same spot. You probably don't want to click it again if you want to keep your rank and not need to restart the week...