Replaced old external drive with new drive several months ago.  New bigger drive has new drive number.  Have done several projects on new drive.  When i go to old projects, the drive listed in the bin is the old drive letter.  Tried deleting msm files and rebuilding but no help. I can't see a way to just change the drive letter listed in the bin.  All i get is OFF LINE.

Are these Avid media master clips or AMA linked clips.

Offline clips will show the last known location for that clip until its relinked to the same media in a different location.

No clips are AMA.  Additionally, i noticed that if i use the media tool to say, erase one of the old projects that shows no clips in the bin, media tool shows dozens and dozens of clips, renders, etc.

How can media tool see everything and my project bins show nothing?  As I may have mentioned before, have reinstalled MC and deleted the two database files on each Avid Mediafiles folders and let MC rebuild them.

You should be able to check these media files are legit by dragging and dropping the msmMMOB database file into an empty bin. 

This will populate your bin with all the master files. If they're not showing as online, you should be able to relink to them.

Did as you suggested.  Projects and sequences now in the bins but come up "Off Line" and are still referencing the old drive number that has been replaced.

Have you tried relinking the master clips?

there's a lot of tutorials that cover this, if you do a quick search.

For example...

https://www.youtube.com/watch?v=FUCfU4ewAlA