2006 Prius Died on Freeway

Hey everyone. Just to preface this, I am NOT a car guy at all, and I'm sorry if this had been posted before. I scrolled through and read some of the threads, but none of them seemed to match with me exactly so I thought I'd post myself.

Last week, my 2006 Prius with 190,000 miles dash just went black while going 65 on the freeway. It lost power and I had to coax it off to the side of the road. No warning lights came on and there were no sounds, but I thought I might've smelled a slight electrical burning right before the dash went black, but when we lifted the hood I couldn't ssmell anything anymore. I called some friends and we tried to troubleshoot it for two hours without success before having to tow it back to my house.

When we were troubleshooting, we noticed the gas was low and so was the oil. I had planned on getting an oil change over the weekend for the car, so didn't think it was a big deal. I'm hoping the engine didn't seize up but maybe it did and I'm a complete idiot. Other than gas and oil, we tried to jump the car but that didn't work and the car literally won't start. So possibly the battery is donezo? We also checked the fuzes but they all seemed fine. The headlights were still working at that point and so were the hazard lights, but now they won't come on and it's been a week.

So my question is: Does anyone know what's wrong? What would be the best, cheapest way to troubleshoot what happened? I don't have the money to tow it to a dealership at all.