I tried reconnect all missing links and still not finding them. Too many to search individually. What do I do now? Will a system restore undo this?
A System Restore function in Windows is not designed to restore data files, which a LR catalog and photos would be. It saves changes to programs and system settings.
Where were the photos located, on an internal drive or an external or secondary drive?
Which version of PSE you have? Which OS?
Are those files going missing in your organizer catalog? Where are they imported from? From an external hard disk? From network location?