How can I find a picture?

The easiest way is searching of the photo if you know a rough timeline of when the photo was taken, such as month, year, date. You can also search by other metadata such as location, people, objects. You can also filter your camera roll by photos, videos, screenshots etc. Last resort you can scroll along your camera roll which should be sorted by when you took it or added it.

Does the picture have something distinctive — or at least that would reduce the total number of photos to search through — such as a tree or truck or text or a specific person, or a well-known location? If so, search for it in the Photos app search box.

In addition to the built-in tools in Photos already meantioned by Zachyy and MrHoffman, you may want to look at these pages of the iPhone user guide ( Find photos and videos by date and the following pages)

It helps to organize your photos right after taking them. When we remember where we put a photo, we do not have to search for it, like in real life. To keep your Photos Library tidy and easier to use, I recommend to create folders and albums for special purposes.

• How to create albums and folder is described here: Create and work with photo albums on iPhone
• You may also help Photos to get the dates and locations right. When we add shared photos or downloaded photos to our Photos Library, the photos may not have been tagged correctly. We can correct the capture date and the location: See photo and video information on iPhone
• The caption field of a photo is very useful when searching for certain photos - I am adding distinctive words to the caption, to use them as keywords when searching.
• To focus on certain photos, we can sort and filter the library: Sort and filter the photo library on iPhone

If you are having a Mac as well as an iPhone and are keeping your devices in sync with iCloud Photos, it will be easier to organize your photos your Mac and let your albums, folders, and captions sync with iCloud to your iPhone as well.

Please read the following user tip and restate your question/problem in detail: 

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