external hard drive now read only after el capitan update

After updating to El Capitan yesterday, my toshiba external hard drive is now only giving me permission to "read only". How do I fix this? I have wedding photos I need to be able to access to edit!

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howapple - hello

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i finally ran disc utility and did the first aid on my external hard drive. i copied everything over to my other working hard drive just in case as i didn't want anything to happen to those files. it ran first aid for about 10 seconds and it was fixed!

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