Why does my stereo in my car restart every time I start my car?

I can offer two possibilities.
1) The power connection is incorrect . In general after market radios get their power from two places in the fuse box: 12V (or BATT) , and ACC (or IGN), The 12V lead is supposed to be on all the time. That is what keeps your radio’s memory alive. I’m guessing either the 12V connection is disconnected or connected to IGN.

2) If the radio is connected properly, the next thing to check is the voltage at the 12V lead when you are cranking. It is possible your battery is getting weak and is drawing the 12V line down below the threshold needed for the radio. Use a Volt meter to verify the voltage stays above 10V when you are cranking .

I think @LuckyGuy covered it.

I’m pretty sure they wouldn’t design the stereo to be a constant vampire current drain on the car battery. It sounds more like either the BIOS is malfunctioning or (more likely) the internal BIOS battery has died, clearing the settings each time the car starts. The former can be fixed by flashing the BIOS, the latter by replacing the internal battery.

The keep-alive memory draws minimal current. It is sometimes used to power the clock display as well. It’s a vampire load but more like a mosquito, a milliamp or so. I did not look at the wiring diagram for this particular stereo.
I’m guessing the OP’s foot hit the fuse panel and knocked the 12V spade connector loose.

Please let us know what you find.

Thanks for the help!

Yeah, that sounds like a bad wiring issue to me. I think that if the battery were weak enough for cranking to cause a “brownout” bad enough to bork your presets, you’re about to have bigger issues with your car in the near future.

Your memory wire is likely wired in parallel with the 12v power wire or not wired at all. This is a common mistake. I installed audio systems for a living while in school and saw this all the time.