hi i did backup on my iphone 5 and i lost about 400 photos.how can i bring those photos back?

If you run out of space, you can upgrade your storage. You can also manage your storage space by reducing your iCloud backup size, deleting photos or videos, or deleting files stored in iCloud.

What iCloud backs up

iCloud automatically backs up the information on your devices—iPhone, iPad, and iPod touch—over Wi-Fi every day when they are turned on, locked, and connected to a power source. With your device information backed up in iCloud, you can easily set up a new device or restore information on one you already have.

Here’s what iCloud backs up:

• Purchase history for music, movies, TV shows, apps, and booksYour iCloud backup includes information about the content you have purchased, but not the purchased content itself. When you restore from an iCloud backup, your purchased content is automatically downloaded from the iTunes Store, App Store, or iBooks Store. Some types of content aren’t downloaded automatically in all countries, and previous purchases may be unavailable if they have been refunded or are no longer available in the store. For more information, see the Apple Support article iTunes in the Cloud, iTunes Match, and iTunes Radio availability. Some types of content aren’t available in all countries. For more information, see the Apple Support article What can I buy from the iTunes Store in my country?.
• Photos and videos on your iOS devices, unless you turn on iCloud Photo Library on your iOS device (iOS 8.1 or later). If you turn on iCloud Photo Library, your photos and videos are already stored in iCloud, so they aren’t included in your iCloud backup.
• Device settings
• App data
• Home screen and app organization
• iMessage, text (SMS), and MMS messages
• Ringtones
• Visual Voicemail
• Health data
• HomeKit configuration

Your iOS device backup only includes data and settings stored on your device. It doesn’t include data already stored in iCloud, for example, contacts, calendars, bookmarks, mail messages, notes, shared photo albums, iCloud Photo Library, My Photo Stream, and documents you save in iCloud using iOS apps, Mac apps, and apps on iCloud.com. If your iOS device isn’t set up for iCloud Drive, but is set up for iCloud Documents & Data, your documents stored in iCloud are backed up.