Hey Shelia -
I've never heard of anyone running into this, but looked through old cases our support people have worked. I did find one instance where someone had the same problem when connecting to Excel. We use the same engine to connect to both Excel & Access, so it's probably the same issue.
In this particular instance we weren't able to figure out exactly WHY this problem was occuring, but the person who opened the case was able to get going again by re-creating a new data source from SCRATCH which included the "new" table they wanted to use. They then "swapped out" the old data source for the new one with this technique:
You might want to give this a try too. Reading between the lines, it almost sounded like something inside the excel workbook (and and potentially in your access database) had changed, and that "messed us up" somehow. Unfortunately, the user didnt' have a "before" version of the Excel workbook, so there was nothing to compare against.
Let us know if this works, and good luck!
If you're running with a 64 bit version of Office 2010/2013, it may require downloading the Microsoft Database Engine driver. After I installed it on my machine, the error was resolved.
The driver is located here: Drivers & Activation | Tableau Software.