I have DOT in my portfolio and it is down 79% as of today. The amount I've put there is quite big for me. The average buy price per DOT is 25.80USD. The price of DOT today is 5.38.
So the question is what are my options to rescue the money I've put into it? Is there anything I can do or I just wait?
First of all, are you in dire need of money? If yes, then you may be forced to sell, otherwise I don't see a reason not to wait. Did you acquire many coins that put your financial state in a tough situation? If none of these apply, then I'd simply hold your coins and wait for a recovery. Polkadot's ATH was at approximately $50, which means that it has a decent potential for a recovery. Although you have purchased exactly in the middle, the current price is possibly the lowest it could be at the time, as it was unfortunately affected by the SEC lawsuit.
My advice, simply hold and if you're up to invest any further, I'd use the DCA technique that other users suggested. In that way, you'll lower your average purchase price, while it's a great opportunity now that it's affordable.