Hello bonbontintin,
100% disk is likely referring to your hard disk/ hard drive. It means you've run out of storage space. You should delete at least 10-15% of your files that are taking up your hard drive space as soon as you can to give your hard disk some relief. This can usually be found by heading to Start menu > File Explorer > This PC > OS C:/ drive.
Do you have a lot of movies, music, etc. on the computer? If so try deleting some of those files and it should solve your problem.