If you did not delete the photos on your iPhone or any other device that is logged in with your Apple ID, then they are still on iCloud. You can try and toggle the Photos in iCloud switch so whether that kickstarts the download from iCloud process.
Ensure that you are logged in with your Apple ID on your iPhone. Open Settings ➡️ Apple ID (Your Name at Top) ➡️ iCloud ➡️ Photos ➡️ Sync this iPhone: Here, this switch needs to be ON. If it is ON, then toggle it OFF and then back to ON. See whether that starts the process where you can begin seeing your photos in the Photos app.
If the above does not work, then from a web browser on your iPhone or another device, go to 👉 www.icloud.com and sign in with your Apple ID. Go to Photos once you are signed in. Check to see whether your photos actually exist on iCloud.
Axel F.