Have you tried deleting your wallet file and restoring it again? Or tried to changing your Electrum server manually?
If you are sure that this address belongs to you, then you are safe. You just need to see how can you let Electrum know that those coins are there.
If you can't fix, you could do this:
Go to your Addresses tab, right click the address that received those coins and select "Private Key"; Import the private key in another wallet software and see if you can spend the coins.
Sorry for the late reply, it's been a while since I had time to tinker with this.
I've used Bither and imported the private key as you suggested, Bither shows a 0,00 balance for this address.
I'm really puzzled now as when I click the link from the Bither app to go to the blockexplorer (
https://blockchain.info/address/1Hefr1NLzABVZhK9Kh7XSB55xRFtK5ex6e)...
AGAIN, it shows 0,5 BTC but it doesn't show up in Bither OR Electrum?
I haven't tried restoring the wallets yet but at this point I don't see how it would make a difference?
Blockexplorer sees 0,5 balance - 2 different wallet apps see 0,00.
Any other suggestions?