Despite what you may think, @AMANDA, it does matter. You have made big changes, but you have not shared what they are. From what can be seen, you have added bank accounts, enabled more tabs, and deleted all your transactions. Somewhere, something is in the database that is interfering with your ability to import a bank statement, but you have destroyed all evidence of where or what that might be.
The most likely place to look for the problem previously was in the journal entries. I definitely did not suggest that you delete them. I only said the evidence told me you were misusing journal entries. Now that they are gone, we will never know.
My current suggestion is that you start over by creating a brand new business. You presently have no transactions entered. So the only things you will need to do are recreate the chart of accounts and define your bank accounts (whether there are one or three). Be sure to follow the Guides as you do that. Then try again.