All rankings removed from Google - Serious Issue - HELP

One of the sites I manage recently(19th or 20th) lost all its rankings and It seems like It's completely removed from Google without any prior notice or any info on Search console. What could be the possible reason?

 

In my opinion, if your rankings have suddenly fell tremendously than you are penalized by Google. And I don't mean manual action penalty.

 

What type of penalty could that be?

 

Actually, we track the ranking of keywords every week and we had nearly 10 keywords ranking in the first position and 20 keywords ranking in 1std and 2nd page but on 19th we rechecked the ranks of the keywords and all keywords had lost ranks. They didn't reduce instead they were completely gone from those keywords ranking. We had moved from http to https 2 months back. Search console manual actions don't show anything & I checked SEO health on various sites and it all showed above 90%.

This domain had alot of sub-domains. Could it cause any issue?

 

Without seeing your site its kind of impossible to say. And sub-domains are considered as separate domains by the search engines.

 

If I were you, I would go and investigate. I'd check out if there's something wrong I did, or if maybe Google caught something that they thought was something's fishy, or if they devalued some of your links, or you had some site problems. Go check it out!

 

Maybe Google have penalized you or you have done something wrong while submitting backlinks, or mighty you have done some changes in your site. There might be many reasons for your problems. Checked your site onne more time might you found solution to your problem.