Your best bet would probably be to re-change the drive letter back to "I", then make sure that all of your files' tags match the database (by using Update tags from Library with everything selected), then change the drive letter back to "F". After that, open up your Media Library, remove all the files (Select All --> Delete --> Remove from Library), then re-import.
Before you try this, I suppose it would be worth it to try selecting all the missing files in your current situation, and trying "Move/Copy File" and pointing them at the new location. I wouldn't get my hopes up, but this would be worth a shot.
It would be nice if MC offered an option to "re-link" missing files that had been moved, as this happens to me fairly often. I have scripts that move and organize my "new" files automagically. Often though, I will import the files into MC (to preview them) prior to these scripts being run. Once the scripts do run, I end up with all these missing files in the DB. It would be nice to be able to select the missing files, right click and choose "Re-Link Missing Files", have a dialog where you choose the drive/directory to search, and click go. I'm thinking of functionality much like the "Reconnect Media" function in Final Cut Pro.