I'm not finding a forum for your specific model, so let me try and help here for now.
To clear your cache, power down your phone. You may have to remove the battery. Then press and hold the volume up button and then press the power button and keep holding them both until the phone boots into recovery mode.
Use the volume up/down buttons to move your selection to 'wipe cache partition' and then use the power button to select this. You may see a confirmation menu to make sure that's what you want to do. once you've confirmed this, it will erase your cache and bring you back to the main menu. From there select reboot and see if that fixed your problem. If not, you might have to perform a factory reset. Be advised that a factory reset will erase your current data so make sure you've backed up first (if possible).
You can see step-by-step instructions
here.