If you see the welcome file, then your vault seems correct. The question is now: where have you stored your files in.
You can check the sitze of your encrypted vault folder. If it is just a view KB (like the welcome file), then you probably haven’t stored your files in the vault because then the vault is empty.
If the vault is bigger that the welcome file, then you might read this.
Please search your system for the files as well maybe you stored these files by accident somewhere that isn’t in fact the vault.
Although it does not help with this problem, I have to say that it not understandable for me how files can be classified as „extremely important“ but then not backup is set up. Please do your backups. Think about when your pc burns down. All will be lost.