Answer:
That depends on you and your therapist. Psychotherapy takes work and sometimes a significant amount of time. Of course, this varies with the problems that need addressed, but usually it can last anywhere from weeks to years. If you put effort into psychotherapy, it works. If you don't, psychotherapy will not work. I also believe it depends on the therapist you have. A good therapist will listen, build your trust, will not be judgmental, and will help you address your problems head on. He or she will give you good advice, good resources, and help you understand what's going on. If you are debating on whether or not to participate in psychotherapy, go for it. There is nothing to lose.
Take care