i checked in electrum files and default_wallet is empty file.
maybe it bkz i have old version in my PC too and it have conflict with just downloaded version?
Which OS? I'm going to assume Windows 7 or earlier.
Try this. To to Start -> Run..., type this and then press OK:
%appdata%
This will open up an Explorer window. Find the Electrum folder and rename it to Electrum-old (right click, Rename). Then start up Electrum again.
If you don't have any BTC in your old Electrum, you can delete Electrum-old at some point (at your own risk).
Tnank You very much !
Solved