It looks like I broke my Arduino (Compatible) Pro Mini board using AtmelStudio to change the fuses. I was having trouble with speed and using some basic sketches. For example, the LED blink was on for 2 seconds and off for 2 seconds instead of 1 second. I tried to change the fuses to Ext Clock + 65 ms, and now I can't use the thing at all. Cannot enter programming mode. Any ideas?
Sounds like you broke your fuses.
You may be able to enter programming mode by applying an external clock signal to the clock in pin (use another Arduino to generate it). If that doesn't work then the only way to fix it is with a "High Voltage Programmer".
Nick Gammon has a very good tutorial here: http://www.gammon.com.au/forum/?id=12898