Will deleting data from my iphone storage also delete it from icloud storage?

I'm a little confused about what you did so please correct me if I am wrong.

1. You did not delete any data yourself.
2. You were asked to sign out of Apple ID / iCloud (this is very surprising but I'll take your word for it)

If the above is correct, you only need to sign back in Apple ID / iCloud by opening Settings, taping your name at the top and following the on-screen instructions to sign you in.

Yes, if you synch that data to iCloud. If you want to prevent it, go to Settings> [your name] > iCloud and turn off any type of data you no longer want to synch.

Yes.

I was invited to do an update and backup, but was asked to sign in also. Then was asked to sign out which I did only to find that most of my pictures was gone not to mention important information

Question is how do I get everything back as before?

How to get deleted pictures or information back again?