The computer is not able to open the photo library for repair...

If you cannot find the library as outlined by Tony, we really need to know more to understand why the library has vanished.

What has happened directly before Photos could no longer find the library? Did you just upgrade to a new system version? Which system version is running on your Mac?

Have you been using iCloud Photos?

Where have you been keeping the Photos Library? If you kept the Photos Library on an external volume, make sure, the external volume is compatible with Photos as described here: Move your Photos library to save space on your Mac - Apple Support. The recent system versions are no longer allowing us to keep the Photos Library on an incompatible volume.

You will need to tell us how the library came to be lost. Though if it is actually lost (Rather than moved somewhere photos can't find it) the only way back will be from your most recent backup.

First try opening photos while holding the option key. Is more than one library listed. If so, open them in turn to see if any contain your photos.

If not, then use the spotlight search to see if there are any other libraries (search in finder). Put photoslibrary in the searchbox.

Make sure "this mac" is selected.

If you click on the found libraries in turn, the location will be shown at the bottom of the finder window. Open each one to see if they contain your images. (Use the option key to start photos then select the library)