There is no quick way of straighten a tooth and obviously not in a week. Don't attempt any teeth-straightening on your own as you can risk a pain or further complications without necessary knowledge. This require training and long-term practice. If this would be so simple, orthodontist wouldn't study that topic.
If your tooth is slightly twisted, there is some reason for it. Either you've another tooth either underneath (you can't know that without a proper X-Ray) or next to it or there is no really space for your tooth (and you need a palatal spreader to widen the upper jaw), or there is some potential complication and you can end up with dental extraction.
So make sure that you make an appointment with your your orthodonist before making a decision. There is no better person who can tell you the options than your orthodontist (always be open for a second opinion).
Today, one of the most popular options for realigning teeth (excempt traditional braces) is to use a clear retainer or brace appliance (such as Invisalign, Damon System, etc.). Or you can get a holding arch to prevent teeth from shifting.
If you're looking for any brace-less techniques, the only one is by gently massaging the teeth and gums every day in intended direction. However if you're not confident, please consult that with your orthodontist.