I closed my client and when I reopened it, a new wallet was shown with no transactions.
Any idea what's going on here. Completely lost
I tried to open a wallet backup and now it says "The error message was 'null'"
When I've seen this thread I rushed to warn you about this, but I may be late now.
Multibit is buggy. If you manage to open a copy of your wallet I urge you export the private key(s) and import into Electrum. When you regain with this method the control on your funds, you can do transactions again. And you will also have options to set the amount for tx fee.