The drive can be reformatted by partition. I would look this up as it's too long to explain here and I am not familiar with your particular drive. If that doesn't work you should be able to just re-load them on there if you have the non-corrupted files else where.

For future reference: You should be able to ctrl +shift + esc (to bring up the 'Windows Task Manager') go to 'Appliations' and quit whatever program thinks the drive is using it. If that doesn't work you can go to 'Processes' in the same window and end whatever is causing the drive to not want to eject. Then you should be able to safely eject 29b00a99-7710-4268-9d2c-ca2781304967_46.jpg. Or you might see a large green arrow icon that does the same thing essentially, but it will tell you what's causing the error, might be a specific program or might be "system".