Your drive could be failing, don't know, not sure.
The catalog file is just a Database file. It Does Not hold all your images. Those are stored someplace on your drive, Not in the LR catalog file. You need to copy both all your images and the LR catalog file to some other drive, like an external drive.
The LR catalog file is usually stored, by default, in your Username folder, Pictures under Adobe then Lightroom.
DriveLetterOrName / (Mac) \ (Windows) YourUserName>Pictures>Adobe>Lightroom
As for your images only you know where you stored them.