Updating user permissions

Hi all, I am currently a software engineering student and last week I was able to work with files using the terminal. However starting today when I tried to do go into a folder using the terminal it said "request denied". so I go into the terminal's information and I have been removed from the permissions and when I went to add myself again it said "the operation can't be completed because I don't have the necessary permissions".

Updating user permissions
 
 
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