Lost photos from Iphoto to photo

If you open the iPhoto library in photos (hold down the option key when starting photos so you can select it), then Photos will convert it so it can be opened in the Photos app.

I'd advise making a backup of the library first.

Do you have more than one iPhoto Library? Then you will need to create Photos Libraries from all of them by opening each of them in turn in Photos. You can easily switch between Photos Libraries as described in the paragraph "Switch between Libraries" in the user guide: Create additional photo libraries in Photos on Mac - Apple Support

When you open an iPhoto Library in Photos, the new library will be created in the same folder as the original iPhoto Library. before you open an iPhoto Library, check, if its location is compatible with Photos and if there is enough free storage. During the conversion Photos may need a lot of additional storage.If the iPhoto Library is on an external volume, the volume needs to meet these requirements: Move your Photos library to save space on your Mac - Apple Support

find my pictures

Please start your own topic and give us a *lot* more detail.