Quote from: Reid on Today at 03:41:25 PM

You are using Electrum.
Try seeking help here.

It is useless to seek help. Nobody can help him.

Those coins were already transferred to another address. Bitcoin transactions are irreversible.

Quote from: Rex717 on Today at 02:58:26 PM

It's my first message and I'm crying...

I had about 3.5 bitcoin, I tried to use some a short while ago and got a message that there is a compulsory upgrade.

I downloaded and installed the upgrade on my iMac, restarted Electrum, and then it happened...

There is one thing you can do: Get informed.

You had 3.5 bitcoins. For about 0.006 btc you can buy a ledger nano (https://shop.ledger.com/ buy only in this website).
The price of the proper security equipment for your investment is about 0.17% of what you invested.

A hardware wallet is, without a doubt, the best and most secure way to store your bitcoins. I strongly recommend one.