Reinstall Office 2019

Hello,
I still have my key, I am told that this key is already in use.
Thank you

The first time I installed it, I had to use phone activation, and since it recognizes my PC, I just have to enter the key and it goes through directly.

Have you changed your motherboard?

No, I didn't change anything. I just formatted my PC.

Or maybe your key is not a valid retail box version.

You might have been duped with a VL version (volume licenses).

Otherwise, you can contact Microsoft; they offer customer service for retail versions.

I don't really know what else to say.

No, I have a key in a box: that is to say, I was supposed to download Office from office.com/setup by logging in with my account, which I forgot, and enter my key.
So I forgot my credentials (email and password).
Thank you again.

Do you have the phone activation option?

On the phone, the robot asks you how many PCs it is installed on, you answer one

You say or enter the code, then they give you a code in return.

Hello.
No, I don't have an activation option by phone. I installed it with an account I forgot, so I'm looking for solutions. If you could help me, I would be very grateful. Thank you so much.

Yes, I have the same problem.
I bought a new computer and had Office 2019 installed.
Six months later, my hard drive failed and was replaced, so I lost my Office.
Since then, I haven't been able to reinstall it.
Since it wasn't me but the store that installed it, I don't know which email it was installed with or the password or key.
Big problem that I can't resolve.
Good luck.