The ear phone jack can wear out, I found a replacementI use my Grace Digital Mondo with ear phones very often, and it finally stopped working, in that it would cut the speaker off...
Answer to: My tablet turned off now it will not turn back on how do I fix itYou did not say if you changed the battery. Does the screen show that the battery is charging when you connect power? The quality of the answer you get is in direct relation to the quality of the question. Give little information, and you get little information. In any case, the battery is my first question, but only because you never mentioned it and it is the most obvious first suspect part. if the tablet was dropped, or used by a child, which could mean it was dropped, that is another reason for it to stop working. Try charing it, and post the results here. This should include if the display shows that the battery is changing, or not. Good luck