how can i recover pictures that are kept in iphoto, this app does not open anymore ?

iPhoto was discontinued 7 years ago. It is no longer developed or sold. It was replaced by the more powerful (and free) Photos.app that comes with the OS. You can migrate to that app very simply:

Hold down the option (or alt) key and launch Photos. From the resulting menu select 'Choose Library' and point at your iPhoto Library. It will do the rest.

If you prefer not to use Photos there are several 3rd party apps that you can use. Which to choose depends on the kind of photographer you are and your budget.

Which system version do you have installed? The method described by Yer_Man will work on any system version up to macOS 12, but no longer on macOS 13 Ventura. On Ventura all you can do to get access to the Photos in an iPhoto Library, is to import the photos from the iPhoto Library into a Photos Library. That will save the photos, but not the albums and events and the keywords.

On macOS Venture launch Photos, let it create a new Photo Library, if you do not yet have one, then use "File > Import" and select the iPhoto Library (not the iPhoto.app). Photos will now show photos for importing, that are not yet in your Photos Library. It will take a very long time for the new photos to appear, if your iPhoto Library is large.

Did you try to start up in Safe Mode and let macOS diagnose itself and correct issues?

How to use safe mode on your Mac - Apple Support

Are you using iCloud Photos? If yes, you can log into your iCloud account one your browser and open the Photo app, to transfer the photos to your Mac.

Léonie: Does importing get Master and Version, linked?