Why Ranking is dropped of my website?

Why Ranking is dropped of my website?

Rank drop since?
what activities you have done to recover rankings and what activities you were doing before that?

Give answer to the question so that we can understand the situation and suggest you the best solution.

Because of
You’re tracking the wrong rankings.
Low quality links.
Losing good links.
Bad hosting.
Incorrect robots.txt file.
more Competitors
Google update.