Website down after moving my domain to Cloudflare registrar

Hi,

I have transfered my domain name to Cloudflare registrar and my website is now down. It was originaly with 1&1 (where my site is hosted) and after moving my domain name and the transfer was completed, it went offline.
I can’t find any topic or anyone for that matter in a similar situation.
Can you please help

Regards

Domain?