Hi there,
Like Alexey said, you need to make sure the name of the .psx file and the .files folder (the one Agisoft creates automatically when you create a .psx file) are the same, otherwise the .psx file won't open.
That being said, changing the name of the parent folder will not matter at all. At worst, it will break the links to your photos. If you want to check the status of the links to your photos, just double-click on one of them within the .psx. If the name change went without a hitch, then all will be fine. If the name change broke the links, you will get a blurry photo and an error message. In that case, just right-click on a photo in the photo pane and select "Change Path...". From there, select the option you want (whether you want to update the path to just one photo, all the photos in the chunk, or all the photos) and navigate to where the photos are stored. This should fix all the broken links.
Cheers,