My wallet is stored on a thumb drive.  I just tried to open it.  It's been named default wallet since I got it several years ago.  When I opened it, the message said that file does not exist.  I closed out and started over.  The next time and every time since, when I open the folder, it says this folder is empty.  That folder contained all files for the wallet.  I downloaded another wallet 4.0.9 from electrum.org.  When I attempted to open it, it says that file does not exist.  How do I proceed to getting my wallet back?  I have seed and password.