Delete the blockchain_headers and config file found here:

C:\Users\XXXX\AppData\Roaming\Electrum\

Start electrum. If it doesn's start then take a look at your default_wallet file using a text editor like notepad. Can you see human readable text? It should look something like this:


The above is just an example. Your addresses most likely start with 1. The point being that it should be readable text. Do you see something like this?