Missing Data in Itunes - Bad ID3V2

In itunes the data such as album, year, genre etc. are missing for about a third of my music. When I import the mp3's into mp3tag it comes up with BADID3V2. However all the data appears to be there when I look at the files in explorer. This never used to be missing in itunes.Below is the screengrabs showing the missing data in itunes and mp3tag, but explorer shows the data is there. Can any-one help me sort these? I don't want to have to use MP3tag to add data to 3000 songs.

Try uploading a very short file that exhibits the problem to some place where it could be downloaded. Perhaps someone can examine it and find the problem and suggest how to fix it.

Were these files always like this in iTunes and Mp3tag, or did some software operating on the files corrupt the ID3v2 tag?

Unfortunately, Mp3tag usually isn't much use in either diagnosing or fixing corrupted tags.

Download the appropriate version of this program MP3val and run a few mp3's through there.

There website states:
"MP3val is a small, high-speed tool for MPEG audio files validation and (optionally) fixing problems. It was primarily designed for verification of MPEG 1 Layer III (MP3) files, but supports also other MPEG versions and layers. It can be useful for finding corrupted files (e.g. incompletely downloaded).'