if u are sentenced to jail for 8 years serving 30 percent and u did a plea ag

Without knowing the specifics of your case, it is difficult to answer the question. As a general rule, if you enter a plea to a charge you can not seek post conviction relief untess you have a certified question that was reserved at the time that you entered you plea or you are alleging ineffective assistance of counsel. You can not file for post conviction relief just because you don't like what happened. You have to have specific mistakes that were made in order to be granted post conviction relief. Even if  you file the request that doesn't mean that it will be granted because very few are granted.