Check Hold Button
Check that you haven't accidentally put the system into Hold mode; if your buttons aren't responding but the screen is still active, the Hold mode is the most likely culprit. The mode disables all the buttons to keep you from accidentally hitting buttons or turning the system on while it's in your bag. Hold mode is enabled when the power slider is pressed all the way down; push it up a notch to stop the hold function. Once out of hold, the buttons respond as usual.
Wait
If the system has stopped responding, give it a few minutes to see if the system wakes up. As with a computer, sometimes the device needs a minute to work through the processes already running before it can handle more. If the system does not respond after a few minutes, reboot it.
Reboot the System
To reboot the system, hold the power button as far up as you can until the system turns off entirely. It takes about 10 seconds before the screen goes black and the indicator lights turn off. In other versions of the PSP, you could also remove the battery if a hard reset fails, but the PSPgo does not offer an accessible battery. In the unlikely situation that the hard reset fails, wait for the battery to drain on its own. Once turned off, let the system rest for a couple of minutes before turning the system back on.
Update Your System
System updates provided by Sony not only add new features to your firmware but also fix errors that can cause system malfunctions. If you're running out-of-date firmware, you can either run the System Update option and install the update via the Internet, or you can download the update onto your computer from the PlayStation website and load it onto the PSP Go system via USB. If loading the file manually, go to the "PSP" folder, then "Game," and save the file in "Update."
Avoid the Circumstances
Most of the time the system freezes when it is overloaded by too many tasks or commands, so if you're playing a game, avoid extraneous mashing of buttons outside of gameplay. Obviously, fighting games lend themselves to the button-mashing style of gameplay. If you're in the XMB menu and it freezes, allow a task to complete before trying to start a new one. If you're using "homebrew" applications, you're more likely to encounter crashes and freezes, as these applications are user-made.