Using IOS Developer Certificates for running an app on iPhone

hello everyone,

I am trying to run a simple app on my iPhone 7. I created the app in Xcode, of course (on my iMac).

The problem is that I a deleted my private certificate keychain (or something like that).

Therefore in Xcode, when I click on "Manage Certificates, the status of all the IOS Developer Certificates is "Missing Private Key" (The one that i deleted).

However, when I click on the plus button in order to create a new IOS Developer Certificates I gets an error which says "You already have a current iOS Development certificate or a pending certificate request."

Moreover, i can't figure out how to delete those certificates....

This is how it looks in the Xcode:

Does someone have a solution to this problem? How can I finally run my app on my iPhone (Without IOS Developer account!)?