Was it a builtin toolbar?

If yes, then when you renamed the excel.xlb file, then excel will start fresh.

If it was a customized toolbar, how was it created--by a macro or was it a
toolbar you attached to a workbook?  Or did you just create it manually?

In either of those first two cases, you should be able to rerun the macro or
open the workbook with the attached toolbar.

If it was a customized toolbar that you built by hand, then you may have to
recreate that.

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I'm guessing that it was a builtin toolbar and you renamed some of the *.xlb
files, but not the one that excel was really using.

Try Windows Start Button|Find|and search your pc for *.xlb (remember to search
through hidden folders for hidden files, too.)

Then rename them and restart excel and see what happens.

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Tools|customize|Toolbars tab
selecting the offending toolbar
Clicking reset maybe less destructive next time.