Sometimes God has to close a door because He knows that if He don't that we won't move forward. We all go through tough times... ALL OF US DO. When these times come, try to remember that no pain comes that God won't use for a greater purpose. Also remember, just because you’re struggling doesn’t mean you’re failing. Every time you find success you will also find that you had struggles to overcome in order achieve it, so keep your head up, God's not finished with you yet.
"God causes everything to work together for the good of those who love God and are called according to his purpose for them". (Romans 8:28)