I tried plugging in my cellphone headphones into my USB port on my desktop pc, and got an overload message. However, I wasn't able to use my mouse or keyboard. I waited a while to see if anything would change and I unplugged it, but nothing happened. I then restarted my computer(using the power button) and on startup I heard a loud beeping and it would not boot up. I'm sure I fried something, but I'm not sure what to do.

Please specify your OS.

How did you fit cellphone headphones into a USB port? My cellphone headphone jack is a circular jack, much different than a USB connection.