My daughter 13yrs of age had skipped school for 2days and forged letter to her teacher stating her absence. She has a very strong character and even after we asked her she never apologies and merely replied that she wanted to stay at home.

This points to a specific issue that needs resolving rather than a child pushing the boundaries of rebellion. Have you tried speaking to her in a safe space way (ie you arent in trouble, but we are worried)? If she is still not willing to share, perhaps the next step is to either speak with her close friend (if you know them well) or to call the school and make an appointment to see the headteacher - this could be something as simple as she is embarrassed about something that happened, or more sinister (and therefore needs dealing with quickly) such she may be being bullied. Good luck! And please share with us what the reason was, so we can all learn from this. Thank you!