My time capsule froze. Won't start. If I rest the machine, will I lose all the data that was backed up on the time capsule?
No data is lost by any reset.
If it froze what is the LED doing at the front?
If it has gone off, give us the model of the TC from the rubber foot.. A1xxx
You are likely seeing a dead power supply.
If it is a later model then it is more likely actual hard drive issue which could mean your files are gone.
Important if the front LED is solid amber that can indicate a dead drive.
Leave the TC to cool down for a few hours and then try restarting it.