A spinning logo usually indicates that an image cannot be found (perhaps due to an incorrect path in the gallery's XML file or a missing image on the web server).
If your gallery was working fine but now is not (and you have made no changes), then this suggests that something might have happened on your web server to cause the problem.
First of all, check that the paths to the images in your gallery's XML file are correct and that your images are present in their correct locations on your web server.
You might like to also contact your web host to ask if they have changed anything or have been experiencing any issues lately which might be contributing to your problem (maybe they have had some reason to reinstate your website from an incomplete backup).
If you continue to experience difficulties, please post back with the URL to your gallery's web page so that I can see the problem for myself and hopefully help further.
Thank you.