The last time you shut calibre down it was using (the pen) drive F:
Drive F: may no longer be available (either not there or has a different latter)
The message implies that Calibre was trying to create a 'default' library on the (now missing) drive used for Libraries (not everyone, uses C: for personal data)
When using removable drives with a calibre session, remember to switch back to the builtin drive Library before shutting down to avoid this issue.
assuming you copied the whole Library folder from the pen drive. Start calibre from the commandline with:
Code:
calibre --with-library c:\users\<yours>\<library folder> \;Use the library located at the specified path.