Any concept what’s going on with my Exterior arduous drive?

I’ve used this for possibly 2 years and has labored. Each Since my xbox one s has been getting slightly run down from the years. it has taken a toll on the Exterior arduous drive I consider (laggy/glitchy/recreation crashes). However the exterior arduous drive says it’s 100% full, however 0.0 GB free (No video games on the exterior storage). Any concept what the issue is? In order that I don’t have to purchase a brand new one?