Peace, i have found when i get frustratated, its time to take a break, a fresh ear is always good to correct mistakes. If you aren't feeling what you are creating, just take a breather remember why you want to create music in the first place, and then ask yourself, whatever it is you are creating does it fit into what you were originally trying to express. If not then look for what is causing you to feel like that, after all you need to love your own expression. Everytime you review it you will be getting one step closer to creating that you wish to hear.
Stay positive understand we all end up cocking up, making mistakes and sometimes are just generally not in any type of mood to make music. Trust your own guidence !!!