If you need to just view something quickly you can use:
but otherwise, you can use:
chown being change owner, -R being recursive (i.e make all sub-directories as well), your username is the user you want to change it to, and location is where the file or directory is located (probably something like /dev/sdba4).
chown -R <username> <location>
Note: I think you have to run it as root for it to work, in which case use:
to obtain a root shell.
PS: These things are always a pain, the developers must find a way to make graphic integration in nautilus so you can open root folders with authentication and easily change permissions.