Hi, I have lost my phone, please help to know how can i get access my photos saved in icloud.

If you had iCloud Photos turned on in the phone, you can use any computer internet browser and log into iCloud.com and go to the Photos app there. You can also turn on iCloud Photos in a replacement phone or other device and the photos will sync to it. See: Set up and use iCloud Photos - Apple Support

If you didn't have iCloud Photos turned on in the phone but did have an iCloud Backup, you can't view the contents of the backup but you can use it to setup a new device. See: Use iCloud to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support