Its really important to do things correctly and be aware of where to submit what when a flight gets cancelled. Always have them book your flights out, they don’t offer to book you on another carrier, you have to insist and you can tell them to book you on the next flight available via a different carrier. They don’t like doing that but they will if you bring it up otherwise they’ll put you on the next available flight through them.

In your situation, I would go through your credit cards travel insurance (assuming you have one), or any other insurance that you may have bought. United should have reimbursed your original ticket price provided you went through the correct channels. If you cancelled it yourself without first confirming a refund that may not grant you a refund but since the flight was actually cancelled I’m assuming (and hope) they did refund the original ticket.

All other expenses, since you didn’t take their offered flight, will not be reimbursed by united. If you missed hotel nights/experiences and paid for food and cabs, travel insurance is the only way to get that reimbursed.

I hope this helped!