Criminal Defense Attorney
It is generally difficult to withdraw a guilty plea in Oregon, assuming that you have already been sentenced. If you had an attorney at the time you entered the guilty plea, you should contact them. Otherwise, you can try the Oregon State Bar lawyer referral service (http://www.osbar.org/public/ris/ris.html) to find an attorney who can advise you based on the specific facts of your case.
Car / Auto Accident Lawyer
I agree - it is hard to withdraw a guilty plea. You should contact an attorney to review and assist you.