PR will automatically find all files that are in the same directory structure as the first one you select. If another file is not in that directory structure, it will prompt you again for the next file it does not find. If you have lots of directories that not in the same structure as before, you must tell it where the file is for each one.
For example, assume the files are named File1.avi, File2.avi , etc. And some files are in directory H:\My Videos\This Project\Day 1\ and others in H:\My Videos\This Project\Day 2\. Once PR is pointed to a file in Day 1, it will also find all the files in Day 2 etc.
If you responded with one of the "options" (e.g. "offline all") or you pointed PR to some files on the new "G" drive, skipped the rest, saved the file, and then changed the drive back to "H," you may get odd results.
Do you have a saved copy of the project file from before you started trying to relink? You might go back to that one and see if you can relink more successfully?