cannot install software

[Adam7]

File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 768, in simulate
    return self._simulate_helper(trans, status_path)
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 936, in _simulate_helper
    return depends, status, self._cache.required_download, \
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 218, in required_download
    pm.get_archives(fetcher, self._list, self._records)
SystemError: E:I wasn't able to locate file for the ttf-mscorefonts-installer package. This might mean you need to manually fix this package.

When I tried to install restricted extras to play DVDs an end user agreement came up from ms, and i couldn't seem to accept the terms so i think i pressed a wrong button, i am a new ubuntu user, so have very little knowledge, but really like it, so please help!